#include<bits/stdc++.h>
#define MAXN 2007
using namespace std;
int n,t[MAXN][MAXN],ans;
int pr0[MAXN][MAXN],pr1[MAXN][MAXN];
int pref[MAXN][MAXN];
int sumrect(int a,int b,int c,int d){
return pref[c][d] - pref[a-1][d] - pref[c][b-1] + pref[a-1][b-1];
}
pair<int,int> findrect(int row,int s,int t){
int l=0,r=row,tt;
while(l+1<r){
tt=(l+r)/2;
if(sumrect(tt,s,row,t)==0){
r=tt;
}else{
l=tt;
}
}
int up=r;
l=row; r=n+1;
while(l+1<r){
tt=(l+r)/2;
if(sumrect(row,s,tt,t)==0){
l=tt;
}else{
r=tt;
}
}
int down=l;
return {up,down};
}
/// maxarea if current maximal rectangle lies on row x and stop in col y
int dp[MAXN][MAXN];
int height[MAXN][MAXN],from[MAXN][MAXN],to[MAXN][MAXN];
stack<int> st;
void calc_rectangles(int row){
height[row][0]=height[row][n+1]=-1;
for(int col=1;col<=n;col++){
if(t[row][col]==1)height[row][col]=0;
else height[row][col]=height[row-1][col]+1;
}
while(!st.empty())st.pop();
st.push(0);
for(int col=1;col<=n;col++){
while(!st.empty() and height[row][col]<=height[row][st.top()]){
st.pop();
}
from[row][col]=st.top()+1;
st.push(col);
}
while(!st.empty())st.pop();
st.push(n+1);
for(int col=n;col>=1;col--){
while(!st.empty() and height[row][col]<=height[row][st.top()]){
st.pop();
}
to[row][col]=st.top()-1;
st.push(col);
}
}
int ff(int row,int col){
int area=height[row][col] * (to[row][col] - from[row][col] + 1);
int top=row-height[row][col];
dp[row][col]=area;
if(top>0){
int endr=pr0[top][to[row][col]];
while(endr>=from[row][col]){
int endl=max(pr1[top][endr]+1,from[row][col]);
auto rect=findrect(top,endl,endr);
int coll=pr1[rect.first-1][endr];
if(coll==0)coll=endr;
dp[row][col] = max( dp[row][col] , ff(rect.second,coll) - (endr-endl+1) * height[row][col] + area);
endr=pr0[top][pr1[top][endr]];
}
}
if(row<n){
int endr=pr0[row+1][to[row][col]];
while(endr>=from[row][col]){
int endl=max(pr1[row+1][endr]+1,from[row][col]);
auto rect=findrect(row+1,endl,endr);
int coll=pr1[rect.first-1][endr];
if(coll==0)coll=endr;
dp[row][col] = max( dp[row][col] , ff(rect.second,coll) - (endr-endl+1) * height[row][col] + area);
endr=pr0[row+1][pr1[row+1][endr]];
}
}
return dp[row][col];
}
int biggest_stadium(int N, vector< vector<int> > F){
n=N;
for(int i=1;i<=n;i++){
for(int f=1;f<=n;f++){
t[i][f]=F[i-1][f-1];
pref[i][f]=t[i][f]+pref[i][f-1]+pref[i-1][f]-pref[i-1][f-1];
}
}
for(int i=1;i<=n;i++){
int s0=0,s1=0;
for(int f=1;f<=n;f++){
if(t[i][f]==0)s0=f;
else s1=f;
pr0[i][f]=s0; pr1[i][f]=s1;
}
}
for(int i=1;i<=n;i++)calc_rectangles(i);
for(int i=1;i<=n;i++){
for(int f=1;f<=n;f++){
ans=max(ans,ff(i,f));
}
}
return ans;
}
/*int main(){
cout<<biggest_stadium(5, {{0, 0, 0, 0, 0},
{1, 0, 0, 0, 0},
{0, 0, 0, 0, 0},
{0, 0, 0, 0, 0},
{0, 0, 1, 0, 0}})<<"\n";
return 0;
}*/
