#include<iostream>
#include<vector>
#include<algorithm>
#include "soccer.h"
using namespace std;
const int MAX_N=2e3+3;
int a[MAX_N][MAX_N];
bool tmp[MAX_N][MAX_N];
int n;
bool used[MAX_N][MAX_N];
int dx[]={0,+1,0,-1};
int dy[]={-1,0,+1,0};
int empsz;
void dfs(int i,int j)
{
used[i][j]=1;
for(int id=0;id<4;id++)
{
int ni=i+dx[id],nj=j+dy[id];
if(ni<0 or ni>=n or nj<0 or nj>=n)continue;
if(used[ni][nj] or tmp[ni][nj]==0)continue;
dfs(ni,nj);
}
}
bool ok(int phase,int x,int y)
{
int ni=x+dx[phase],nj=y+dy[phase];
if(ni<0 or ni>=n or nj<0 or nj>=n)return 0;
if(tmp[ni][nj]==0)return 0;
return 1;
}
bool check()
{
int x=-1,y;
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
if(tmp[i][j] && x==-1)
{
x=i;
y=j;
}
used[i][j]=0;
}
}
int phase=0;
int times=10*n;
while(times--)
{
used[x][y]=1;
if(phase==4)break;
while(1)
{
used[x][y]=1;
if(ok((phase+1)%4,x,y))
{
x+=dx[(phase+1)%4];
y+=dy[(phase+1)%4];
used[x][y]=1;
}
else
{
phase++;
break;
}
while(ok(phase,x,y))
{
x+=dx[phase];
y+=dy[phase];
used[x][y]=1;
}
}
}
int cnt=0;
//cout<<"\n";
for(int i=0;i<n;i++)
{
int f=-1,s=-2;
for(int j=0;j<n;j++)
{
//cout<<used[i][j];
if(used[i][j])
{
if(f==-1)f=j;
s=j;
}
}
//cout<<"\n";
for(int j=f;j<=s;j++)
{
cnt+=tmp[i][j];
}
}
if(cnt==empsz)return 1;
return 0;
}
int biggest_stadium(int N, std::vector<std::vector<int>> F)
{
n=N;
for(int i=0;i<n;i++)
{
for(int j=0;j<n;j++)
{
a[i][j]=F[i][j];
if(a[i][j]==0){empsz++;tmp[i][j]=1;}
}
}
if(check())return empsz;
return -1;
}
