#include "soccer.h"
#include <cassert>
#include <cstdio>
#include <algorithm>
#include <vector>

int biggest_stadium(int N, std::vector<std::vector<int>> F) {
	std::vector<int> L(N, N + 1), R(N, -1);
	int ans = 0;
	for(int i = 0;i < N;++i) {
		int l = 0, r = N - 1;
		for(;r >= 0 && F[i][r] == 1;) -- r;
		if(r < 0) {
			continue;
		}
		for(;l < N && F[i][l] == 1;) ++ l;
		for(int j = l;j <= r;++j) {
			if(F[i][j]) return 0;
		}
		L[i] = l, R[i] = r;
		ans += r - l + 1;
	}
	int max = max_element(R.begin(), R.end()) - R.begin();
	int min = min_element(L.begin(), L.end()) - L.begin();
	for(int i = max;i >= 1;--i) if(R[i - 1] > R[i]) return 0;
	for(int i = max;i + 1 < N;++i) if(R[i + 1] > R[i]) return 0;
	for(int i = min;i >= 1;--i) if(L[i - 1] < L[i]) return 0;
	for(int i = min;i + 1 < N;++i) if(L[i + 1] < L[i]) return 0;
	std::vector<std::pair<int, int>> ranges;
	for(int i = 0;i < N;++i) 
		if(L[i] < N) ranges.emplace_back(L[i], R[i]);
	sort(ranges.begin(), ranges.end(), [](auto x, auto y) {
		return x.second - x.first > y.second - y.first;
	});
	for(int i = 1;i < (int) ranges.size();++i) {
		auto x = ranges[i - 1];
		auto y = ranges[i];
		if(y.first < x.first || y.second > x.second) return 0;
	}
    return ans;
}

#ifdef zqj
int main() {
	freopen("1.in", "r", stdin);
    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