#include <bits/stdc++.h>   using namespace std;   const int N = 5100;   char Map[N][N];   int dp[N][N];   int main() {     int i, j;     int line, row;     scanf( %d%d , &line, &row);     for (i = 0; i < line; i++) scanf( %s , Map[i]);     for (i = 0; i < line; i++) {       for (j = row - 1; j >= 0; j--) {         if (Map[i][j] ==  1 )           dp[j][i] = dp[j + 1][i] + 1;         else           dp[j][i] = 0;       }     }     int ret = 0;     for (i = 0; i < row; i++) {       sort(dp[i], dp[i] + line);       for (j = 0; j < line; j++) {         ret = max(ret, (line - j) * dp[i][j]);       }     }     printf( %d n , ret);     return 0;   }   