1 #include<bits/stdc++.h>
2 using namespace std;
3 const int N=2000;
4 int n,m,k,l[N],r[N],h[N],a[N*N],ans,kk;
5 char s[N][N];
6 int main() {
7 scanf("%d%d", &n, &m);
8 for (int j=0;j<m;j++){
9 l[j]=-1;
10 r[j]=m;
11 }
12 set< pair<pair<int, int>, int> > ss;
13 for (int i = 0; i < n; i++) {
14 scanf("%s", &s[i]);
15 k = -1;
16 for (int j = 0; j < m; j++) {
17 l[j] = max(k, l[j]);
18 if (s[i][j] == '1') {
19 h[j]++;
20 } else {
21 h[j] = 0;
22 l[j] = -1;
23 k = j;
24 }
25 }
26 k = m;
27 for (int j = m - 1; j >= 0; j--) {
28 r[j] = min(r[j], k);
29 if (s[i][j] == '0') {
30 k = j;
31 r[j] = m;
32 }
33 }
34 ss.clear();
35 for (int j = 0; j < m; ++j) {
36 ss.insert(make_pair(make_pair(l[j], r[j]), h[j]));
37 }
38 for (auto item : ss) {
39 a[++kk] = item.second * (item.first.second - item.first.first - 1);
40 a[++kk] = item.second * (item.first.second - item.first.first - 2);
41 a[++kk] = (item.second - 1) * (item.first.second - item.first.first - 1);
42 }
43 }
44 sort(a+1, a+kk+1 ,greater<int>());
45 printf("%d
",max(0,a[2]));
46 }
