#include <bits/stdc++.h>
using namespace std;
const long long INF=1e18;
const int N=2510;
int v[N][N],u[N][N],d[N][N],l[N][N],r[N][N];
int32_t main() {
int n,m;cin>>n>>m;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
char c;cin>>c;
v[i][j]=c-'0';
}
}
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
if(v[i][j]==0){
continue;
}
u[i][j]=u[i-1][j]+1;
l[i][j]=l[i][j-1]+1;
}
}
for(int i=n;i>0;i--){
for(int j=m;j>0;j--){
if(v[i][j]==0){
continue;
}
d[i][j]=d[i+1][j]+1;
r[i][j]=r[i][j+1]+1;
}
}
int a=N,b=N;
for(int i=1;i<=n;i++){
for(int j=1;j<=m;j++){
if(v[i][j]==0){
continue;
}
a=min(a,r[i][j]+l[i][j]-1);
b=min(b,u[i][j]+d[i][j]-1);
//cout<<r[i][j]<<' '<<l[i][j]<<' '<<u[i][j]<<' '<<d[i][j]<<endl;
}
}
cout<<a*b<<endl;
return 0;
}
