diff --git a/最后一舞/C语言基础进阶合集版编程题.md b/最后一舞/C语言基础进阶合集版编程题.md
index 150cc42..d4f9e61 100644
--- a/最后一舞/C语言基础进阶合集版编程题.md
+++ b/最后一舞/C语言基础进阶合集版编程题.md
@@ -457,6 +457,35 @@ int main(){
 方阵中主对角线、副对角线的索引和方阵的行、列有什么关系？
 ```
 
+```c
+#include <stdio.h>
+
+int main(){
+	int n, s = 0;
+	scanf("%d", &n); 
+	int a[n][n];
+	
+	for(int i=0;i<n;i++){
+		for(int j=0;j<n;j++){
+			scanf("%d", &a[i][j]);
+		}
+	}
+	
+	for(int i=0;i<n;i++){
+		for(int j=0;j<n;j++){
+			if(i != n-1 && j != n-1 && i+j != n-1){
+				s += a[i][j];
+			}
+		}
+	}
+	
+	printf("%d\n", s);
+
+	return 0;
+}
+
+```
+
 
 
 ### 10 矩阵乘积