diff --git a/step_4_insert.c b/step_4_insert.c
new file mode 100644
index 0000000..ba08be5
--- /dev/null
+++ b/step_4_insert.c
@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+struct student
+{
+    int id;
+    int class;
+    float score_math;
+    float score_phi;
+    float score_eng;
+    bool isinserted;
+};
+
+
+ void sort(struct student a[],int count){
+    struct student temp;
+    for(int i = 0;i < count-1;i++){
+        for(int j = i+1;j<count-1;j++){
+            if(a[j].class > a[j+1].class){
+                temp = a[j];
+                a[j] = a[j+1];
+                a[j+1] = temp;
+            }
+        }
+    }
+    for (int m = 0; m < count-1; m++) {
+    for (int n = m + 1; n < count-1; n++) {
+        if (a[n].class == a[n+1].class) {
+            float sum1 = a[n].score_math + a[n].score_phi + a[n].score_eng;
+            float sum2 = a[n+1].score_math + a[n+1].score_phi + a[n+1].score_eng;
+            if (sum1 < sum2 || (sum1 == sum2 && a[m].id > a[n].id)) {
+                struct student temp = a[n];
+                a[n] = a[n+1];
+                a[n+1] = temp;
+            }
+        }
+    }
+}
+}
+void printgrade(struct student a[],int count){
+    for(int i = 0;i<count;i++){
+        printf("%d  %d  %.1f  %.1f  %.1f",a[i].id,a[i].class,a[i].score_math,a[i].score_phi,a[i].score_eng);
+        if(a[i].isinserted){
+            printf(" inserted\n");
+        }
+        else{
+            printf("\n");
+        }
+    }
+}
+
+
+int main(){
+    struct student grade[4];
+    grade[0].id = 10001;
+grade[0].class = 11;
+grade[0].score_math = 99.5;
+grade[0].score_phi = 88.5;
+grade[0].score_eng = 89.5;
+grade[0].isinserted = false;
+
+grade[1].id = 10002;
+grade[1].class = 12;
+grade[1].score_math = 77.9;
+grade[1].score_phi = 56.5;
+grade[1].score_eng = 87.5;
+grade[1].isinserted = false;
+
+grade[2].id = 10003;
+grade[2].class = 11;
+grade[2].score_math = 92.5;
+grade[2].score_phi = 99.0;
+grade[2].score_eng = 60.5;
+grade[2].isinserted = false;
+    scanf("%d %d %f %f %f",&grade[3].id,&grade[3].class,&grade[3].score_math,&grade[3].score_phi,&grade[3].score_eng);
+    grade[3].isinserted = true;
+    int count = 4;
+    sort(grade,count);
+    printgrade(grade,count);
+    return 0;
+
+
+}
\ No newline at end of file