#include "soccer.h"
#include<bits/stdc++.h>

using namespace std;

typedef int ll;

ll biggest_stadium(ll n, vector<vector<ll>> f) {
	bool isu = false;
	ll nl = n + 1, nr = -1;
	vector<pair<ll, ll>> otrs;
	ll col = 0;
	for (ll i = 0; i < n; i++) {
		ll l = n + 1, r = -1;
		for (ll j = 0; j < n; j++) {
			if (f[i][j] == 0) {
				col++;
				if (l == n + 1) {
					l = j;
				}
				r = j;
			}
		}
		for (ll j = l; j <= r; j++) {
			if (f[i][j] == 1) {
				return n * n + 1;
			}
		}
		if (r < nr || l > nl) {
			isu = true;
		}
		if (isu) {
			if (r > nr || l < nl) {
				return n * n + 1;
			}
		}
		if (r != -1) {
			while (!otrs.empty() && otrs.back().first <= l && r <= otrs.back().second) {
				otrs.pop_back();
			}
			if (!otrs.empty() && (otrs.back().first < l || r < otrs.back().second)) {
				return n * n + 1;
			}
			otrs.emplace_back(l, r);
		}
		nl = l;
		nr = r;
	}
	return col;
}

#ifdef LOCAL
int main()
{
    int N;
    assert(1 == scanf("%d", &N));
    std::vector<std::vector<int>> F(N, std::vector<int>(N));
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            assert(1 == scanf("%d", &F[i][j]));
        }
    }
    fclose(stdin);

    int res = biggest_stadium(N, F);

    printf("%d\n", res);
    fclose(stdout);
    return 0;
}
#endif