Given a matrix (H × W) which contains only 1 and 0, find the area of the largest rectangle which only contains 0s.

Constraints

* 1 ≤ H, W ≤ 1,400

Input


H W
c1,1 c1,2 ... c1,W
c2,1 c2,2 ... c2,W
:
cH,1 cH,2 ... cH,W


In the first line, two integers H and W separated by a space character are given. In the following H lines, ci,j, elements of the H × W matrix, are given.

Output

Print the area (the number of 0s) of the largest rectangle.

Example

Input

4 5
0 0 1 0 0
1 0 0 0 0
0 0 0 1 0
0 0 0 1 0


Output

6
#include <bits/stdc++.h>
int H, W;
int C[1400][1400];
int dp[1400][1400];
int min(int a, int b) {
  if (a < b)
    return a;
  else
    return b;
}
int max(int a, int b) {
  if (a < b)
    return b;
  else
    return a;
}
int largest() {
  int i, j;
  int maxwidth = 0;
  for (i = 0; i < H; i++) {
    dp[i][0] = (C[i][0] == 1) ? 0 : 1;
  }
  for (j = 0; j < W; j++) {
    dp[0][i] = (C[0][i] == 1) ? 0 : 1;
  }
  for (i = 1; i < H; i++) {
    for (j = 1; j < W; j++) {
      if (C[i][j])
        dp[i][j] = 0;
      else {
        dp[i][j] = min(dp[i - 1][j - 1], min(dp[i - 1][j], dp[i][j - 1])) + 1;
        maxwidth = max(maxwidth, dp[i][j]);
      }
    }
  }
  return maxwidth * maxwidth;
}
int main() {
  int i, j;
  scanf("%d %d", &H, &W);
  for (i = 0; i < H; i++) {
    for (j = 0; j < W; j++) {
      scanf("%d", &C[i][j]);
    }
  }
  printf("%d\n", largest());
  return 0;
}
