#include <bits/stdc++.h>

using namespace std;
int main()
{
    const
    int NMAX = 1000;
    int a[NMAX][NMAX];
    int n, kol = 0;
    cin >> n;
    for (int i = 0; i < n; ++i)
    {
        for(int j = 0; j < n; ++j)
        {
            cin >> a[i][j];
        }
    }
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            if(a[i][j] == 1)
            {
                kol ++;
            }
        }
    }
    cout << kol;

}