diff --git a/step4.cpp b/step4.cpp
new file mode 100644
index 0000000..b5a1b6c
--- /dev/null
+++ b/step4.cpp
@@ -0,0 +1,106 @@
+#include <stdio.h>
+
+#define COL 6
+#define GRADEBINGIN 2
+
+int studentMember = 0;
+double storeInformation[100][COL];
+
+void inputStudentInformation(double store[][COL])
+{
+    double* p;
+    int i = 0, j = 0;
+    while (1) {
+        p = &store[i][j];
+        double temp;
+        scanf("%lf", &temp);
+        *p = temp;
+        j++;
+        if (j == COL - 1) {
+            *(p + 1) = 0;
+            printf("One student's information has been, input 0 or 1 to quit or continue.\n");
+            int ch;
+            scanf("%d", &ch);
+            if (ch == 0) { break; }
+            else if (ch == 1)
+            {
+                j = 0;
+                i++;
+                studentMember++;
+            }
+            else {
+                printf("WRONG INPUT,aoto quit\n");
+                break;
+            }
+        }
+    }
+}
+
+double sumScore(double store[][COL], int n) {
+    double sum = 0;
+    for (int i = GRADEBINGIN; i < COL - 1; i++) {
+        sum += store[n][i];
+    }
+    return sum;
+}
+
+void printStudentOriginalScore(double store[][COL])
+{
+    for (int i = 0; i <= studentMember; i++) {
+        printf("%5d  %d %.1f  %.1f  %.1f  %.1f  %s\n", (int)store[i][0], (int)store[i][1], store[i][2], store[i][3], store[i][4], sumScore(store, i), store[i][6] == 1? "":"inserted");
+    }
+}
+
+void printstep2(double store[][COL]) {
+    for (int i = 0; i <= studentMember; i++) {
+        printf("%5d,%.1f,%.1f\n", (int)storeInformation[i][0], sumScore(storeInformation, i), sumScore(storeInformation, i) / 3);
+    }
+}
+
+void insertedNew() {
+    printf("The new student information\n");
+    studentMember++;
+    double* p;
+    for (int i = 0; i < COL - 1; i++) {
+        p = &storeInformation[studentMember][i];
+        double temp = 0;
+        scanf("%lf", &temp);
+        *p = temp;
+    }
+    *(p + 1) = 1;
+}
+
+void manage()
+{
+    printf("                              1.Input\n");
+    printf("                              2.Output\n");
+    printf("                              3.Order\n");
+    printf("                              4.Quit\n");
+    char keywords;
+    keywords = getchar();
+    switch (keywords) {
+    case 'i':
+        printf("Please input info of the three students\n");
+        inputStudentInformation(storeInformation);
+        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 about to Quit\n");
+        break;
+    default:
+        printf("Wrong input\n");
+        break;
+    }
+}
+int main()
+{
+    manage();
+    insertedNew();
+    printStudentOriginalScore(storeInformation);
+    return 0;
+}
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