from collections import deque

W, H = map(int, input().split())
C = [list(input()) for _ in range(H)]

routes = []
for h in range(H-1):
    for w in range(W-1):
        if C[h][w] == '.':
            r = []
            q = deque()
            q.append((h, w))
            C[h][w] = '*' #done
            r.append((h, w))
            while q:
                y0, x0 = q.popleft()
                C[y0][x0] = '*' #done
                r.append((y0, x0))
                for dy, dx in ((-1, 0), (0, 1), (1, 0), (0, -1)):
                    y1, x1 = y0 + dy, x0 + dx
                    if 0 <= y1 < H and 0 <= x1 < W and C[y1][x1] == '.':
                        q.append((y1, x1))
                        C[y1][x1] = '*' #done
                        r.append((y1, x1))
            routes.append(r)

ans = H * W
for p0 in routes[0]:
    for p1 in routes[1]:
        d = abs(p0[0] - p1[0]) + abs(p0[1] - p1[1])
        if d - 1 < ans:
            ans = d - 1

print(ans)