from queue import Queue

def bfs(y, x, C, cave, num):
    Q = Queue()
    Q.put((y, x))
    while not Q.empty():
        n = Q.get()
        if C[n[0]][n[1]-1] == '.' and (n[0], n[1]-1) not in cave[num]:
            cave[num].append((n[0], n[1]-1))
            Q.put((n[0], n[1]-1))
        if C[n[0]][n[1]+1] == '.' and (n[0], n[1]+1) not in cave[num]:
            cave[num].append((n[0], n[1]+1))
            Q.put((n[0], n[1]+1))
        if C[n[0]-1][n[1]] == '.' and (n[0]-1, n[1]) not in cave[num]:
            cave[num].append((n[0]-1, n[1]))
            Q.put((n[0]-1, n[1]))
        if C[n[0]+1][n[1]] == '.' and (n[0]+1, n[1]) not in cave[num]:
            cave[num].append((n[0]+1, n[1]))
            Q.put((n[0]+1, n[1]))
    return

W, H = map(int, input().split())
C = []
for _ in range(H):
    C.append(input())
num = 0
cave = [[],[]]
for y in range(1, H-1):
    for x in range(1, W-1):
        if C[y][x] == '.' and (y, x) not in cave[0] and (y, x) not in cave[1]:
            cave[num].append((y, x))
            bfs(y, x, C, cave, num)
            num += 1
min_dist = float('inf')
for c1 in cave[0]:
    for c2 in cave[1]:
        min_dist = min(min_dist, abs(c1[0] - c2[0]) + abs(c1[1] - c2[1]) - 1)
print(min_dist)