diff --git a/step9.cpp b/step9.cpp
new file mode 100644
index 0000000..0ab18c5
--- /dev/null
+++ b/step9.cpp
@@ -0,0 +1,190 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct Node {
+    char stus[100];
+    int classes;
+    char names[100];
+    double mathGrade;
+    double physicsGrade;
+    double englishGrade;
+    int boolNew;
+    struct Node* next;
+} Node;
+
+Node* head = NULL;
+
+Node* createNode() {
+    Node* newNode = (Node*)malloc(sizeof(Node));
+    newNode->next = NULL;
+    return newNode;
+}
+
+void input(Node* node) {
+    printf("Id ");
+    scanf("%s", node->stus);
+    printf("class ");
+    scanf("%d", &node->classes);
+    printf("name ");
+    scanf("%s", node->names);
+    printf("score1 ");
+    scanf("%lf", &node->mathGrade);
+    printf("score2 ");
+    scanf("%lf", &node->physicsGrade);
+    printf("score3 ");
+    scanf("%lf", &node->englishGrade);
+    node->boolNew = 0;
+}
+
+void inputStudentInformation() {
+    char a[10];
+    do {
+        Node* newNode = createNode();
+        input(newNode);
+        newNode->next = head;
+        head = newNode;
+        printf("One student has been input!\n");
+        printf("continue?(yes/no)\n");
+        scanf("%s", a);
+    } while (strcmp(a, "no") != 0);
+}
+
+void insertedNew() {
+    Node* newNode = createNode();
+    input(newNode);
+    newNode->boolNew = 1;
+    newNode->next = head;
+    head = newNode;
+    printf("One student has been input!\n");
+}
+
+void informationClear(char a[100]) {
+    Node** current = &head;
+    while (*current) {
+        Node* entry = *current;
+        if (strcmp(entry->stus, a) == 0 || strcmp(entry->names, a) == 0) {
+            *current = entry->next;
+            free(entry);
+        }
+        else {
+            current = &entry->next;
+        }
+    }
+}
+
+void sortStudents() {
+    Node* sorted = NULL;
+    Node* current = head;
+    while (current) {
+        Node* next = current->next;
+        if (!sorted || current->classes < sorted->classes ||
+            (current->classes == sorted->classes &&
+                current->mathGrade + current->physicsGrade + current->englishGrade >=
+                sorted->mathGrade + sorted->physicsGrade + sorted->englishGrade)) {
+            current->next = sorted;
+            sorted = current;
+        }
+        else {
+            Node* temp = sorted;
+            while (temp->next &&
+                (temp->next->classes < current->classes ||
+                    (temp->next->classes == current->classes &&
+                        temp->next->mathGrade + temp->next->physicsGrade + temp->next->englishGrade >=
+                        current->mathGrade + current->physicsGrade + current->englishGrade))) {
+                temp = temp->next;
+            }
+            current->next = temp->next;
+            temp->next = current;
+        }
+        current = next;
+    }
+    head = sorted;
+    printf("Students have been sorted!\n");
+}
+
+void printStudentOriginalScore() {
+    Node* current = head;
+    int classs = 0;
+    while (current) {
+        if (current->classes != classs) {
+            printf("%d  %s  %s  %.1f  %.1f  %.1f  %s\n",
+                current->classes, current->stus, current->names,
+                current->mathGrade, current->physicsGrade, current->englishGrade,
+                current->boolNew == 0 ? "" : current->boolNew == 1 ? "inserted" : "modified");
+        }
+        else {
+            printf("    %s  %s  %.1f  %.1f  %.1f  %s\n",
+                current->stus, current->names,
+                current->mathGrade, current->physicsGrade, current->englishGrade,
+                current->boolNew == 0 ? "" : current->boolNew == 1 ? "inserted" : "modified");
+        }
+        classs = current->classes;
+        current->boolNew = 0;
+        current = current->next;
+    }
+}
+
+void modifyStudent() {
+    char a[10];
+    printf("Are you sure(yes/no) ");
+    scanf("%s", a);
+    if (strcmp(a, "yes") == 0) {
+        char stusToModify[10];
+        printf("Enter the student number to modify, followed by new data ( 10001 2 Kobe 59 59 59):\n");
+        scanf("%s", stusToModify);
+
+        Node* current = head;
+        while (current) {
+            if (strcmp(current->stus, stusToModify) == 0) {
+                scanf("%d %s %lf %lf %lf",
+                    &current->classes, current->names,
+                    &current->mathGrade, &current->physicsGrade, &current->englishGrade);
+                current->boolNew = 2;
+                printf("Student data modified successfully!\n");
+                return;
+            }
+            current = current->next;
+        }
+        printf("Student with number %s not found.\n", stusToModify);
+    }
+}
+
+int manage() {
+    printf("1.input\n2.delete\n3.select\n4.order\n5.output\n6.quit\nPlease input your option: ");
+    char keywords;
+    scanf(" %c", &keywords);
+    switch (keywords) {
+    case '1':
+        inputStudentInformation();
+        return 0;
+    case '2': {
+        char a[100];
+        printf("Please enter student's ID or Name: ");
+        scanf("%s", a);
+        informationClear(a);
+        return 0;
+    }
+    case '3':
+        printStudentOriginalScore();
+        return 0;
+    case '4':
+        sortStudents();
+        printStudentOriginalScore();
+        return 0;
+    case '5':
+        printStudentOriginalScore();
+        return 0;
+    case '6':
+        return 1;
+    default:
+        printf("Invalid option. Please try again.\n");
+        return 0;
+    }
+}
+
+int main() {
+    while (manage() == 0) {
+    }
+    return 0;
+}