11.1. Города и дороги

import java.util.Scanner;

public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n, x, s;
        n = sc.nextInt();
        s = 0;
        for (int i = 0; i < n * n; i++) {
            x = sc.nextInt();
            s += x;
        }
        System.out.println(s / 2);
    }
}