from collections import deque
from collections.abc import Iterator


def neighbors4(r: int, c: int) -> Iterator[tuple[int, int]]:
    for dr, dc in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        nr = r + dr
        nc = c + dc
        if not (0 <= nr < H and 0 <= nc < W): continue
        yield nr, nc


def fill(row, col, g, val):
    q = deque([(row, col)])
    while q:
        r, c = q.popleft()
        if g[r][c] == val: continue
        g[r][c] = val

        for nr, nc in neighbors4(r, c):
            if g[nr][nc] == val: continue
            if G[nr][nc] == '#': continue
            q.append((nr, nc))


INF = 1 << 60
W, H = map(int, input().split())
G = [input() for _ in range(H)]

g = [[-1] * W for _ in range(H)]
marker = 0
for i in range(H):
    for j in range(W):
        if g[i][j] != -1: continue
        if G[i][j] == '#': continue
        fill(i, j, g, marker)
        marker += 1

ans = INF
for r1 in range(H):
    for c1 in range(W):
        if g[r1][c1] != 0: continue
        for r2 in range(H):
            for c2 in range(W):
                if g[r2][c2] != 1: continue
                d = abs(r1 - r2) + abs(c1 - c2)
                ans = min(ans, d - 1)

print(ans)