from collections import deque
def bfs():
    for i in range(H):
        for j in range(W):
            if C[i][j] == '.':
                C[i][j] = '#'
                Queue = deque()
                Queue.append((i, j))
                s = [(i, j)]
                while Queue:
                    x,y = Queue.popleft()
                    for i in range(4):
                        nx,ny = x+dx[i],y+dy[i]
                        if C[nx][ny] == '.':
                            C[nx][ny] = '#'
                            Queue.append((nx, ny))
                            s.append((nx, ny))
                return s

dx = [1, -1, 0, 0]
dy = [0, 0, 1, -1]
W,H = map(int,input().split())
C = [list(input()) for _ in range(H)]
s = bfs()
t = bfs()
ans = 1<<16
for sx,sy in s:
    for tx,ty in t:
        ans = min(ans, abs(sx-tx) + abs(sy-ty) - 1)
print(ans)