分别求出N阶方阵a中两个对角线上元素之和。

#include <stdio.h>
#define N 5

void main() {
    int a[N][N], i, j, k = N, pr1 = 0, pr2 = 0;
    for (i = 0; i < N; i++)
        for (j = 0; j < N; j++)
            scanf("%d", &a[i][j]);
    for (i = 0; i < N; i++) {
        pr1 += a[i][i];
        k = k - 1;
        pr2 += a[i][k];
    }
    printf("pr1=%d\n", pr1);
    printf("pr2=%d\n", pr2);
}