#include <iostream>
using namespace std;
int main() {
    int arr[3][3] = {{1,2,3},{4,5,6},{7,8,9}};
    int sum = 0;
    for(int i = 0; i < 3; i++) {
        for(int j = 0; j < 3; j++) {
            if(i == j) {
                sum += arr[i][j];
            }
        }
    }
    cout << sum << endl;
    return 0;
}