#include int main(){ int a[100][100] = {0}; int n, i, j, sum = 0; scanf("%d", &n); for(i = 0;i < n;i++) for(j = 0;j < n;j++) { scanf("%d", &a[i][j]); if(i == j || i+j == n-1) sum += a[i][j]; } printf("两条对角线元素之和 %d\n", sum); return 0;}