Problem:
Largest Square

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

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 square.

Constraints

1 ≤ H, W ≤ 1,400

Sample Input

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

Sample Output

4

Solution in Ruby (judge verdict: Wrong Answer)

h, w = STDIN.gets.split.map(&:to_i)
c = h.times.map { STDIN.gets.split.map(&:to_i) }
dp = (h+1).times.map { (w+1).times.map { 0 } } 

(1..h).each do |i| 
  (1..w).each do |j| 
    p i, j
    if c[i-1][j-1] == 0
      dp[i][j] = [dp[i-1][j-1], dp[i-1][j], dp[i][j-1]].min + 1 
    else
      dp[i][j] = 0 
    end 
  end 
end

puts dp.flatten.max**2