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

4

n, m = map(int, input().split())
grid = [list(map(int, input().split())) for _ in range(n)]
dp = [[0]*m for _ in range(n)]
max_sq = 0
for i in range(n):
    for j in range(m):
        if grid[i][j] == 1:
            if i == 0 or j == 0:
                dp[i][j] = 1
            else:
                dp[i][j] = min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1]) + 1
            max_sq = max(max_sq, dp[i][j])
print(max_sq ** 2)