#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int nmax=2505;
string s[nmax];
int n,m,i,j,p,mn1,mn2;
int main()
{
ios_base::sync_with_stdio(false);
cin>>n>>m;
for(i=1;i<=n;i++)
{
cin>>s[i];
s[i]="0"+s[i]+"0";
}
for(i=1;i<=m+2;i++)
s[0]+='0',s[n+1]+='0';
mn1=n+m,mn2=n+m;
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
{
if(s[i][j]=='1'&&s[i][j-1]=='0')
{
p=j;
while(s[i][p]=='1')
p++;
if(p-j<mn1)
mn1=p-j;
}
if(s[i][j]=='1'&&s[i-1][j]=='0')
{
p=i;
while(s[p][j]=='1')
p++;
if(p-i<mn2)
mn2=p-i;
}
}
if(mn1==n+m)
cout<<"0";
else cout<<mn1*mn2;
return 0;
}
