diff --git a/1.c b/1.c
new file mode 100644
index 0000000..985b634
--- /dev/null
+++ b/1.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+
+struct Data
+{
+	int ID;
+	float score1;
+	float score2;
+	float score3;
+} stu[1001];
+int stl = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+void Question1() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-3].ID, stu[stl-3].score1, stu[stl-3].score2, stu[stl-3].score3, total(&stu[stl-3]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-2].ID, stu[stl-2].score1, stu[stl-2].score2, stu[stl-2].score3, total(&stu[stl-2]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-1].ID, stu[stl-1].score1, stu[stl-1].score2, stu[stl-1].score3, total(&stu[stl-1]));
+
+}
+
+int main() {
+	printf("                              1.Input\n");
+	printf("                              2.Output\n");
+	printf("                              3.Order\n");
+	printf("                              4.Quit\n");
+	char t;
+	scanf("%c", &t);
+	switch(t) {
+		case 'i':
+		printf("You are trying to Input info\n");
+		break;
+		case 'o':
+		printf("You are trying to Output info\n");
+		break;
+		case 'm':
+		printf("You are trying to Make things ordered\n");
+		break;
+		case 'q':
+		printf("You are trying to Quit\n");
+		break;
+		default:
+		printf("Wrong input\n");
+		break;
+	}
+}
\ No newline at end of file
diff --git a/2.c b/2.c
new file mode 100644
index 0000000..34a9e7c
--- /dev/null
+++ b/2.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+
+struct Data
+{
+	int ID;
+	float score1;
+	float score2;
+	float score3;
+} stu[1001];
+int stl = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+void Question1() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-3].ID, stu[stl-3].score1, stu[stl-3].score2, stu[stl-3].score3, total(&stu[stl-3]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-2].ID, stu[stl-2].score1, stu[stl-2].score2, stu[stl-2].score3, total(&stu[stl-2]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-1].ID, stu[stl-1].score1, stu[stl-1].score2, stu[stl-1].score3, total(&stu[stl-1]));
+
+}
+
+void Typein()
+{
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+int main() {
+	Typein();
+	Typein();
+	Typein();
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-3].ID, stu[stl-3].score1, stu[stl-3].score2, stu[stl-3].score3, total(&stu[stl-3]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-2].ID, stu[stl-2].score1, stu[stl-2].score2, stu[stl-2].score3, total(&stu[stl-2]));
+	printf("%d  %2.1f  %2.1f  %2.1f  %.1f\n", stu[stl-1].ID, stu[stl-1].score1, stu[stl-1].score2, stu[stl-1].score3, total(&stu[stl-1]));
+
+}
\ No newline at end of file
diff --git a/3.c b/3.c
new file mode 100644
index 0000000..1311ed7
--- /dev/null
+++ b/3.c
@@ -0,0 +1,67 @@
+#include <stdio.h>
+
+struct Data
+{
+	int ID;
+	float score1;
+	float score2;
+	float score3;
+} stu[1001];
+int stl = 0, sortstl;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+int main() {
+	printf("                              1.Input\n");
+	printf("                              2.Output\n");
+	printf("                              3.Order\n");
+	printf("                              4.Quit\n");
+	char t;
+	scanf("%c", &t);
+	switch(t) {
+		case 'i':
+		printf("You are trying to Input info\n");
+		Input();
+		break;
+		case 'o':
+		printf("You are trying to Output info\n");
+		break;
+		case 'm':
+		printf("You are trying to Make things ordered\n");
+		break;
+		case 'q':
+		printf("You are trying to Quit\n");
+		break;
+		default:
+		printf("Wrong input\n");
+		break;
+	}
+}
\ No newline at end of file
diff --git a/4.c b/4.c
new file mode 100644
index 0000000..f6be406
--- /dev/null
+++ b/4.c
@@ -0,0 +1,89 @@
+#include <stdio.h>
+
+struct Data
+{
+	int ID;
+	int Class;
+	float score1;
+	float score2;
+	float score3;
+} stu[1001];
+int stl = 0;
+struct Data* stuflag;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+
+	if (a == stuflag) stuflag = b;
+else 
+	if (b == stuflag) stuflag = a;
+}
+
+void Sort() {
+	int i, j;
+	for(i = 0; i < stl-1; i++) {
+		for (j = 0; j < stl-i-1; j++) {
+			if (stu[j].Class < stu[j+1].Class) continue;
+			if (stu[j].Class > stu[j+1].Class || 
+			total(&stu[j]) < total(&stu[j+1])) swap(&stu[j], &stu[j+1]);
+		}
+	}
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+void print1(struct Data* a) {
+	printf("%d %d %2.1f %2.1f %2.1f", a->ID, a->Class,
+					a->score1, a->score2, a->score3);
+	if (a == stuflag) printf(" inserted");
+	printf("\n");
+}
+
+void Insert() {
+	stu[0] = (struct Data){10001, 11, 99.5, 88.5, 89.5};
+	stu[1] = (struct Data){10002, 12, 77.9, 56.5, 87.5};
+	stu[2] = (struct Data){10003, 11, 92.5, 89.0, 60.5};
+	stl = 3;
+	
+	scanf("%d", &stu[stl].ID);
+	scanf("%d", &stu[stl].Class);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+	
+	stuflag = stu + 3;
+	Sort();
+	print1(stu + 0);
+	print1(stu + 1);
+	print1(stu + 2);
+	print1(stu + 3);
+}
+
+int main() {
+	Insert();
+}
\ No newline at end of file
diff --git a/5.c b/5.c
new file mode 100644
index 0000000..e2b1a4e
--- /dev/null
+++ b/5.c
@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <string.h>
+
+struct Data
+{
+	int ID;
+	int Class;
+	float score1;
+	float score2;
+	float score3;
+	char name[101];
+} stu[1001];
+int stl = 0;
+struct Data* stuflag = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+
+	if (a == stuflag) stuflag = b;
+else 
+	if (b == stuflag) stuflag = a;
+}
+
+void Sort() {
+	int i, j;
+	for(i = 0; i < stl-1; i++) {
+		for (j = 0; j < stl-i-1; j++) {
+			if (stu[j].Class < stu[j+1].Class) continue;
+			if (stu[j].Class > stu[j+1].Class || 
+			total(&stu[j]) < total(&stu[j+1])) swap(&stu[j], &stu[j+1]);
+		}
+	}
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+void print1(struct Data* a) {
+	printf("%d %d %s %2.1f %2.1f %2.1f", a->ID, a->Class, a->name, 
+					a->score1, a->score2, a->score3);
+	if (a == stuflag) printf(" inserted");
+	printf("\n");
+}
+
+void Remove(struct Data* r) {
+	for(; r+1 < stu+stl; r++) {
+		*r = *(r+1);
+	}
+	stl--;
+}
+
+void Delete() {
+	stu[0] = (struct Data){10001, 11, 99.5, 88.5, 89.5, "Zhang"};
+	stu[1] = (struct Data){10002, 12, 77.9, 56.5, 87.5, "Yang"};
+	stu[2] = (struct Data){10003, 11, 92.5, 89.0, 60.5, "Liang"};
+	stl = 3;
+	
+	int ID = -1; char name[101];
+	scanf("%s", name);
+	getchar();
+	int NumFlag = 1, i;
+	for(i = 0; name[i]!='\0'; i++)
+		if (name[i] < '0' || name[i] > '9') {
+			NumFlag = 0; break;
+		}
+	if (NumFlag) {
+		sscanf(name, "%d", &ID);
+		name[0] = '\0';
+	}
+	
+	printf("Are you sure(yes/no)?\n");
+	char t;
+	scanf("%c", &t);
+	if (t == 'y') {
+		for(i=0; i<stl; i++) {
+			if(stu[i].ID == ID || name[0]!='\0' && strcmp(stu[i].name, name) == 0) {
+				Remove(stu + i);
+				break;
+			}
+		}
+	}
+	for (i=0; i<stl; i++) {
+		print1(stu + i);
+	}
+}
+
+int main() {
+	Delete();
+}
\ No newline at end of file
diff --git a/6.c b/6.c
new file mode 100644
index 0000000..9f7444c
--- /dev/null
+++ b/6.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <string.h>
+
+struct Data
+{
+	int ID;
+	int Class;
+	float score1;
+	float score2;
+	float score3;
+	char name[101];
+} stu[1001];
+int stl = 0;
+struct Data* stuflag = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+
+	if (a == stuflag) stuflag = b;
+else 
+	if (b == stuflag) stuflag = a;
+}
+
+void Sort() {
+	int i, j;
+	for(i = 0; i < stl-1; i++) {
+		for (j = 0; j < stl-i-1; j++) {
+			if (stu[j].Class < stu[j+1].Class) continue;
+			if (stu[j].Class > stu[j+1].Class || 
+			total(&stu[j]) < total(&stu[j+1])) swap(&stu[j], &stu[j+1]);
+		}
+	}
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+
+
+void Modify() {
+	
+	struct Data t;
+	scanf("%d", &t.ID);
+	scanf("%d", &t.Class);	
+	scanf("%s", t.name);	
+	scanf("%f", &t.score1);
+	scanf("%f", &t.score2);
+	scanf("%f", &t.score3);
+
+	int i;
+	
+	for(i=0; i<stl; i++) {
+		if (t.ID == stu[i].ID) {
+			stu[i] = t;
+			stuflag = stu + i;
+			break;
+		}
+	}
+	Sort();
+	for(i=0; i<stl; i++) {
+		if (i>0 && stu[i].Class == stu[i-1].Class) printf("   ");
+		else printf("%2d ", stu[i].Class);
+		printf("%d %s %2.1f %2.1f %2.1f", stu[i].ID, stu[i].name, 
+					stu[i].score1, stu[i].score2, stu[i].score3);
+		if (stuflag == stu + i) printf(" modified");
+		printf("\n");
+	}
+
+}
+
+int main() {
+	stu[0] = (struct Data){10001, 11, 99.5, 88.5, 89.5, "Zhang"};
+	stu[1] = (struct Data){10002, 12, 77.9, 56.5, 87.5, "Yang"};
+	stu[2] = (struct Data){10003, 11, 92.5, 89.0, 60.5, "Liang"};
+	stl = 3;
+	Modify();
+}
\ No newline at end of file
diff --git a/7.c b/7.c
new file mode 100644
index 0000000..48efc5a
--- /dev/null
+++ b/7.c
@@ -0,0 +1,132 @@
+#include <stdio.h>
+#include <string.h>
+
+struct Data
+{
+	int ID;
+	int Class;
+	float score1;
+	float score2;
+	float score3;
+	char name[101];
+} stu[1001];
+int stl = 0;
+struct Data* stuflag = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+
+	if (a == stuflag) stuflag = b;
+else 
+	if (b == stuflag) stuflag = a;
+}
+
+void Sort() {
+	int i, j;
+	for(i = 0; i < stl-1; i++) {
+		for (j = 0; j < stl-i-1; j++) {
+			if (stu[j].Class < stu[j+1].Class) continue;
+			if (stu[j].Class > stu[j+1].Class || 
+			total(&stu[j]) < total(&stu[j+1])) swap(&stu[j], &stu[j+1]);
+		}
+	}
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+void Print1(int i)
+{
+	printf("%d %d %s %.1f %.1f %.1f\n", stu[i].ID, stu[i].Class, stu[i].name,
+				 stu[i].score1, stu[i].score2, stu[i].score3);
+}
+
+void Search() {
+	int t; char com[101]; 
+	int i;
+	scanf("%d %s", &t, com);
+	switch(t) {
+		case 1: {
+			int from, to;
+			sscanf(com, "%d-%d", &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].Class >= from && stu[i].Class <= to)
+					Print1(i);
+			}
+		}break;
+		case 2: {
+			int from, to;
+			sscanf(com, "%d-%d", &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].ID >= from && stu[i].ID <= to)
+					Print1(i);
+			}
+		}break;
+		case 3: {
+			for (i=0; i<stl; i++) {
+				int flag = 1, j;
+				for (j=0; com[j] != '*'; j++) {
+					if (stu[i].name[j] != com[j]) {
+						flag = 0; break;
+					}
+				}
+				if(flag)
+					Print1(i);
+			}
+		}break;
+		case 4: {
+			float gate;
+			sscanf(com, "%f", &gate);
+			for (i=0; i<stl; i++) {
+				if (total(stu + i) >= gate - 0.01f)
+					Print1(i);
+			}
+		}break;
+		case 5: {
+			int Class, from, to;
+			sscanf(com, "%d.%d-%d", &Class, &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].ID >= from && stu[i].ID <= to)
+				if (stu[i].Class == Class)
+					Print1(i);
+			}
+		}
+	}
+}
+
+
+int main() {
+	stu[0] = (struct Data){10001, 11, 99.5, 88.5, 89.5, "Zhang"};
+	stu[1] = (struct Data){10002, 12, 77.9, 56.5, 87.5, "Yang"};
+	stu[2] = (struct Data){10003, 11, 92.5, 89.0, 60.5, "Liang"};
+	stu[3] = (struct Data){10004, 11, 89.6, 56.9, 90.5, "Cai"};
+	stu[4] = (struct Data){10005, 14, 55.6, 67.9, 98.9, "Fu"};
+	stu[5] = (struct Data){10006, 12, 22.1, 45.9, 99.2, "Mao"};
+	stu[6] = (struct Data){10007, 13, 35.6, 67.9, 88.0, "Zhan"};
+	stl = 7;
+	Sort();
+	Search();
+}
\ No newline at end of file
diff --git a/8.c b/8.c
new file mode 100644
index 0000000..c7bfe78
--- /dev/null
+++ b/8.c
@@ -0,0 +1,245 @@
+#include <stdio.h>
+#include <string.h>
+
+struct Data
+{
+	int ID;
+	int Class;
+	float score1;
+	float score2;
+	float score3;
+	char name[101];
+} stu[1001];
+int stl = 0;
+struct Data* stuflag = 0;
+
+float total(struct Data* a) {
+	return a->score1 + a->score2 + a->score3;
+}
+
+void swap(struct Data* a, struct Data* b) {
+	struct Data t = *a;
+	*a = *b;
+	*b = t;
+
+	if (a == stuflag) stuflag = b;
+else 
+	if (b == stuflag) stuflag = a;
+}
+
+void Sort() {
+	int i, j;
+	for(i = 0; i < stl-1; i++) {
+		for (j = 0; j < stl-i-1; j++) {
+			if (stu[j].Class < stu[j+1].Class) continue;
+			if (stu[j].Class > stu[j+1].Class || 
+			total(&stu[j]) < total(&stu[j+1])) swap(&stu[j], &stu[j+1]);
+		}
+	}
+}
+
+void input1() {
+	scanf("%d", &stu[stl].ID);
+	scanf("%f", &stu[stl].score1);
+	scanf("%f", &stu[stl].score2);
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+
+void Input() {
+	printf("Please input info of three students:\n");
+	input1();input1();input1();
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	if (total(&stu[stl-2]) < total(&stu[stl-1])) swap(&stu[stl-2], &stu[stl-1]);
+	if (total(&stu[stl-3]) < total(&stu[stl-2])) swap(&stu[stl-3], &stu[stl-2]);
+	printf("%d,%.1f,%.1f\n", stu[stl-3].ID, total(&stu[stl-3]), total(&stu[stl-3])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-2].ID, total(&stu[stl-2]), total(&stu[stl-2])/3.0f);
+	printf("%d,%.1f,%.1f\n", stu[stl-1].ID, total(&stu[stl-1]), total(&stu[stl-1])/3.0f);
+}
+
+void Print1(int i)
+{
+	printf("%d,%d,%s,%.1f,%.1f,%.1f,%.1f\n", stu[i].ID, stu[i].Class, stu[i].name,
+				 stu[i].score1, stu[i].score2, stu[i].score3, total(&stu[i]));
+}
+
+void Search() {
+	int t; char com[101]; 
+	int i;
+	scanf("%d %s", &t, com);
+	switch(t) {
+		case 1: {
+			int from, to;
+			sscanf(com, "%d-%d", &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].Class >= from && stu[i].Class <= to)
+					Print1(i);
+			}
+		}break;
+		case 2: {
+			int from, to;
+			sscanf(com, "%d-%d", &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].ID >= from && stu[i].ID <= to)
+					Print1(i);
+			}
+		}break;
+		case 3: {
+			for (i=0; i<stl; i++) {
+				int flag = 1, j;
+				for (j=0; com[j] != '*'; j++) {
+					if (stu[i].name[j] != com[j]) {
+						flag = 0; break;
+					}
+				}
+				if(flag)
+					Print1(i);
+			}
+		}break;
+		case 4: {
+			float gate;
+			sscanf(com, "%f", &gate);
+			for (i=0; i<stl; i++) {
+				if (total(stu + i) >= gate - 0.01f)
+					Print1(i);
+			}
+		}break;
+		case 5: {
+			int Class, from, to;
+			sscanf(com, "%d.%d-%d", &Class, &from, &to);
+			for (i=0; i<stl; i++) {
+				if (stu[i].ID >= from && stu[i].ID <= to)
+				if (stu[i].Class == Class)
+					Print1(i);
+			}
+		}
+	}
+}
+
+void Output() {
+	int i;
+	for(i=0; i<stl; i++) {
+		printf("%d,%d,%s,%.1f,%.1f,%.1f,%.1f\n", stu[i].ID, stu[i].Class, stu[i].name,
+			stu[i].score1, stu[i].score2, stu[i].score3, total(&stu[i]));
+	}
+}
+
+void Typein()
+{
+	printf("Id ");
+	scanf("%d", &stu[stl].ID);
+	printf("class ");
+	scanf("%d", &stu[stl].Class);
+	printf("name ");
+	scanf("%s", stu[stl].name);
+	printf("score1 ");
+	scanf("%f", &stu[stl].score1);
+	printf("score2 ");
+	scanf("%f", &stu[stl].score2);
+	printf("score3 ");
+	scanf("%f", &stu[stl].score3);
+	stl++;
+}
+
+void Delete() {
+	int ID = -1; char name[101];
+	scanf("%s", name);
+	getchar();
+	int NumFlag = 1, i;
+	for(i = 0; name[i]!='\0'; i++)
+		if (name[i] < '0' || name[i] > '9') {
+			NumFlag = 0; break;
+		}
+	if (NumFlag) {
+		sscanf(name, "%d", &ID);
+		name[0] = '\0';
+	}
+	for(i=0; i<stl; i++) {
+		if(stu[i].ID == ID || (name[0]!='\0' && strcmp(stu[i].name, name) == 0)) {
+			struct Data* r = stu + i;
+			for(; r+1 < stu+stl; r++) {
+				*r = *(r+1);
+			}
+			stl--;
+			break;
+		}
+	}
+	Output();
+}
+
+void Select_3() {
+	char com[101];
+	scanf("%s", com);
+	int NumFlag = 1, i;
+	for(i = 0; com[i]!='\0'; i++)
+		if (com[i] < '0' || com[i] > '9') {
+			NumFlag = 0; break;
+		}
+	if (NumFlag) {
+		int num;
+		sscanf(com, "%d", &num);
+		if (strlen(com) > 2) 
+			for (i=0; i<stl; i++) {
+				if (stu[i].Class == num)
+				Print1(i);
+			}
+		else 
+			for (i=0; i<stl; i++) 
+				if (stu[i].ID == num)
+				Print1(i);
+	}
+	else {
+		for (i=0; i<stl; i++) 
+			if (strcmp(stu[i].name, com) == 0)
+				Print1(i);
+	}
+}
+
+int main() {
+	char com[11];
+	while(1) {
+		printf("1.input\n");
+		printf("2.delete\n");
+		printf("3.select\n");
+		printf("4.order\n");
+		printf("5.output\n");
+		printf("6.quit\n");
+		printf("please input your option\n");
+		int t; scanf("%d", &t);
+		switch(t) {
+			case 1: 
+			do{
+				Typein();
+				printf("continue?\n");
+				scanf("%s", com);
+			}while(strcmp(com, "yes") == 0);
+			Sort();
+			break;
+			case 2:
+			do {
+				Delete();
+				printf("continue?\n");
+				scanf("%s", com);
+			}while(strcmp(com, "yes") == 0);
+			break;
+			case 3: 
+			do {
+				Select_3();
+				printf("continue?\n");
+				scanf("%s", com);
+			}while(strcmp(com, "yes") == 0);
+			break;
+			case 4:
+			Sort();
+			Output();
+			break;
+			case 5:
+			Output();
+			break;
+			case 6:
+			return 0;
+			break;
+		}
+	}
+}
diff --git a/png.png b/png.png
new file mode 100644
index 0000000..89dc450
Binary files /dev/null and b/png.png differ