diff --git a/1_E2 step4.c b/1_E2 step4.c
new file mode 100644
index 0000000..8214f45
--- /dev/null
+++ b/1_E2 step4.c	
@@ -0,0 +1,53 @@
+#include<stdio.h>
+#define N 3
+
+struct student
+{
+	int num,cls,flag;
+	float math,physics,english,total;
+};
+
+struct student stu[N+1]={{10001,11,0,99.5,88.5,89.5,277.5},
+						{10002,12,0,77.9,56.5,87.5,221.9},
+						{10003,11,0,92.5,99.0,60.5,252},{}};
+
+void sort(struct student *stu,int n)
+{
+	int i,j;
+	struct student tmp;
+	for(i=0;i<n;i++)
+	{
+		for(j=0;j<n-i-1;j++)
+		{
+			if(((stu+j)->cls>(stu+j+1)->cls)||((stu+j)->cls==(stu+j+1)->cls)&&((stu+j)->total<(stu+j+1)->total))
+			{
+				tmp = *(stu+j);
+				*(stu+j) = *(stu+j+1);
+				*(stu+j+1) = tmp;
+			} 
+		}
+	}
+	return;
+}
+
+int main()
+{
+	scanf("%d",&stu[N].num);
+	scanf("%d",&stu[N].cls);
+	scanf("%f",&stu[N].math);
+	scanf("%f",&stu[N].physics);
+	scanf("%f",&stu[N].english);
+	stu[N].flag=1;
+	stu[N].total=stu[N].math+stu[N].physics+stu[N].english;
+	int check=1,i,n=N+1;
+	for(i=0;i<N;i++) if(stu[i].num==stu[N].num) check=0;
+	if(!check) n--;
+	sort(stu,n);
+	for(i=0;i<n;i++)
+	{
+		printf("%d %d %.1f %.1f %.1f",stu[i].num,stu[i].cls,stu[i].math,stu[i].physics,stu[i].english);
+		if(stu[i].flag) printf(" inserted");
+		printf("\n"); 
+	}
+	return 0;
+}