Города и дороги

#include <bits/stdc++.h>

using namespace std;

const int N = 105;

int n;
int a[N][N];

int main(){
    cin >> n;

    int cnt = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> a[i][j];
            cnt = cnt + a[i][j];
        }
    }

    cout << cnt / 2 << endl;
}