#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<double,double> pdd;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template<typename T> void _do(T x){cerr<<x<<"\n";}
template<typename T,typename ...U> void _do(T x,U ...y){cerr<<x<<", ";_do(y...);}
#define dbg(...) cerr<<#__VA_ARGS__<<" = ";_do(__VA_ARGS__);
const int MOD1=1e9+7;
const int MOD2=998244353;
const ll INF=3e18;
ll fpow(ll a,ll b,ll m)
{
if(!b) return 1;
ll tmp=1;
for(ll cur=a;b;b>>=1,cur=cur*cur%m) if(b&1) tmp=tmp*cur%m;
return tmp;
}
ll inv(ll a,ll m) {return fpow(a,m-2,m);}
#define MottoHayaku ios::sync_with_stdio(false);cin.tie(0);
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define F first
#define S second
#define pb push_back
#define uni(c) c.resize(distance(c.begin(),unique(c.begin(),c.end())))
#define unisort(c) sort(c.begin(),c.end()),uni(c)
//#include "soccer.h"
//int dp[505][505][505];
map<pair<int,pii>,int > dp;
int sum[2005][2005];
int n;
int qry(int lx,int rx,int ly,int ry){return sum[rx][ry]-sum[lx-1][ry]-sum[rx][ly-1]+sum[lx-1][ly-1];}
pii extend(int pos,int l,int r)
{
pii ans;
int ql=1,qr=pos;
while(ql<qr)
{
int mid=ql+qr>>1;
if(qry(mid,pos-1,l,r)>0) ql=mid+1;
else qr=mid;
}
ans.F=ql;
ql=pos,qr=n;
while(ql<qr)
{
int mid=ql+qr+1>>1;
if(qry(pos+1,mid,l,r)>0) qr=mid-1;
else ql=mid;
}
ans.S=ql;
return ans;
}
int calc(int pos,int l,int r)
{
//cout<<pos<<" "<<l<<" "<<r<<"\n";
//if(dp[pos][l][r]!=0)
if(dp.find({pos,{l,r}})!=dp.end()) return dp[{pos,{l,r}}];
pii tmp=extend(pos,l,r);
if(tmp.F<pos)
{
return dp[{pos,{l,r}}]=calc(tmp.F,l,r);
//cout<<pos<<" "<<l<<" "<<r<<": "<<dp[pos][l][r]<<"\n";
//return dp[pos][l][r];
}
int mx=0;
int cur=l;
for(int i=l;i<=r;i++)
{
cur=max(cur,i);
int ql=cur-1,qr=r;
while(ql<qr)
{
int mid=ql+qr+1>>1;
bool valid=0;
if(pos>1&&qry(pos-1,pos-1,i,mid)==0) valid=1;
if(tmp.S+1<=n&&qry(tmp.S+1,tmp.S+1,i,mid)==0) valid=1;
if(valid) ql=mid;
else qr=mid-1;
}
if(ql>=cur) mx=max(mx,calc(pos,i,ql)-(tmp.S-tmp.F+1)*(ql-i+1));
cur=ql+1;
}
return dp[{pos,{l,r}}]=mx+(tmp.S-tmp.F+1)*(r-l+1);
//cout<<pos<<" "<<l<<" "<<r<<": "<<dp[pos][l][r]<<"\n";
//return dp[pos][l][r];
}
int biggest_stadium(int N,vector<vector<int> > F)
{
n=N;
rep1(i,n)
{
rep1(j,n)
{
sum[i][j]=sum[i-1][j]+sum[i][j-1]-sum[i-1][j-1]+F[i-1][j-1];
}
}
int ans=0;
rep1(i,n)
{
ll cur=1;
while(cur<=n)
{
while(cur<=n&&F[i-1][cur-1]==1) cur++;
if(cur>n) break;
int to=cur;
while(to+1<=n&&F[i-1][to]==0) to++;
ans=max(ans,calc(i,cur,to));
cur=to+1;
}
}
return ans;
}
