#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define mkp make_pair
#define in insert
#define er erase
#define fd find
#define fr first
#define sc second
typedef long long ll;
typedef long double ld;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll llinf=(1LL<<62);
const int inf=(1<<30);
const int nmax=3e3+50;
const int mod=1e9+7;
using namespace std;
int n,m,i,j,cur,h[nmax][nmax],v[nmax][nmax],x,y,a[nmax][nmax];
char c;
int main()
{
//freopen("sol.in","r",stdin);
//freopen("sol.out","w",stdout);
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
cin>>n>>m;
for(i=1;i<=n;i++)
{
for(j=1;j<=m;j++)
{
cin>>c;
a[i][j]=(c=='1');
}
}
x=y=inf;
for(i=1;i<=n;i++)
{
for(j=m;j>=1;j--)
{
if(a[i][j])
{
h[i][j]=h[i][j+1]+1;
if(!a[i][j-1])y=min(y,h[i][j]);
}
}
}
for(i=1;i<=m;i++)
{
for(j=n;j>=1;j--)
{
if(a[j][i])
{
v[j][i]=v[j+1][i]+1;
if(!a[j-1][i])x=min(x,v[j][i]);
}
}
}
if(x==inf)rc(0);
cout<<x*y<<endl;
return 0;
}
