#include <bits/stdc++.h>
#ifndef CYBER
#include "soccer.h"
#endif
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("Ofast")

using namespace std;
using namespace __gnu_pbds;

#define lg long long
#define ordered_set	tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

int biggest_stadium(int n, vector<vector<int>> f)
{
	lg pos = 1, ans = 0;
	for(int i = 0; i < n; i++)
		for(int j = 0; j < n; j++)
			ans += !f[i][j];
	if(n > 30)
	{
		for(int i = 0; i < n; i++)
		{
			lg zer = 0, one = 0;
			for(int j = 0; j < n; j++)
			{
				if(!f[i][j])	
				{
					zer = 1;
					if(one)	pos = 0;
				}
				else if(zer)	one = 1;
				if(!pos)	break;
			}
		}
	}
	else{
		for(int i = 0; i < n; i++)
		{
			for(int j = 0; j < n; j++)
			{
				if(f[i][j])	continue;
				for(int k = 0; k < n; k++)
				{
					for(int z = 0; z < n; z++)
					{
						if(f[k][z])	continue;
						if(i == k && j == z)	continue;
						if(i == k)
						{
							for(int g = min(j, z); g <= max(j, z); g++)
							{
								if(f[i][g])	pos = 0;
								if(!pos)	break;
							}
							continue;
						}
						if(j == z)
						{
							for(int g = min(i, k); g <= max(i, k); g++)
							{
								if(f[g][j])	pos = 0;
								if(!pos)	break;
							}
							continue;
						}
						lg l = min(i, k), r = max(i, k);
						if(!f[i][z])	continue;
						if(!f[k][j])	continue;
						pos = 0;
						break;
					}
					if(!pos)	break;
				}
				if(!pos)	break;
			}
			if(!pos)	break;
		}
	}
	return (pos ? ans : -1);
}