#include<stdio.h>

int main()

{

????int arr[3][3] = {{1,2,3},{4,5,6},{7,8,9}};

????int i,j;

????int sum =0;

????for(i=0;i<3;i++)

????????{

?????????????for(j=0;j<3;j++)

????????????{

????????????????if(i==j || i+j==2);

????????????????sum += arr[i][j];

????????????}???

????????}

????????printf("對角線元素之和是：%d\n",sum);

????????return 0;

}