[python] 백준 1051 숫자 정사각형

n,m = map(int, input().split())
sq = []
for i in range(n):
    sq.append(list(map(int,input())))

Max = 1

tmp = i
for y in range(n):
    for x in range(m):
        for i in range(1, min(n,m)):
            if y+i >= n or x+i >= m:
                continue
            if sq[y][x] == sq[y][x+i] == sq[y+i][x] == sq[y+i][x+i]:
                Max = max(Max, pow(i+1,2))

print(Max)