#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=205;
int n,m,a[N][N],t[N];
int check(int x){
int minn=0;
for(int i = x;i<=m;i++){
minn=min(minn,t[i-x]);
if(t[i]>minn) return 1;
}
return 0;
}
int ans;
signed main(){
freopen("long.in","r",stdin);
freopen("long.out","w",stdout);
scanf("%lld%lld",&n,&m);
for(int i =1;i<=n;i++)
for(int j = 1;j<=m;j++)
scanf("%lld",&a[i][j]);
for(int i = 1;i<=n;i++)
for(int j = 1;j<=m;j++)
a[i][j]+=a[i-1][j];
for(int i = 1;i<=n;i++)
for(int j = i;j<=n;j++){
for(int k = 1;k<=m;k++) t[k]=t[k-1]+a[j][k]-a[i-1][k];
int l = 1,r=m,res=0;
while(l<=r){
int mid=(l+r)>>1;
if(check(mid)) res=mid,l=mid+1;
else r=mid-1;
}
ans=max(ans,res*(j-i+1));
}
printf("%lld",ans);
return 0;
}