#include<bits/stdc++.h>
using namespace std;
const int N=202;
int sum[N][N];
int n,m;
int maxx;
int main()
{
    freopen("long.in","r",stdin);
    freopen("long.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            scanf("%d",&sum[i][j]);
            sum[i][j]+=sum[i-1][j-1]-sum[i][j-1]-sum[i-1][j];
            for(int a=1;a<=i;a++)
                for(int b=1;b<=j;b++)
                    if((sum[i][j]-sum[i][b-1]-sum[a-1][j]+sum[a-1][b-1])*1.0/(i-a+1)/(j-b+1)>=0) maxx=max(maxx,(i-a+1)*(j-b+1));
        }
    printf("%d",maxx);
    return 0;
}