# import numpy as np

W, H = map(int, input().split())
l = []
for i in range(H):
    ll = list(input())
    l.append(ll)
flg = 0
for i in range(H):
    for j in range(W):
        if l[i][j] == ".":
            flg = 1
            first_h = i
            first_w = j
            break
    if flg:
        break

l_ikko = []

def search_hole(t, y):
	if l[t][y] == ".":
		l[t][y] = 1
		l_ikko.append([t, y])
		if t - 1 >= 0:
			search_hole(t - 1, y)
		if t + 1 <= H:
			search_hole(t + 1, y)
		if y - 1 >= 0:
			search_hole(t, y - 1)
		if y + 1 <= W:
			search_hole(t, y + 1)

     
search_hole(first_h, first_w)
l_niko = []

d_min = 100

for i in range(H):
	for j in range(W):
		if l[i][j] == ".":
			l_niko.append([i, j])

for i in range(len(l_ikko)):
	for j in range(len(l_niko)):
		d_min = min(d_min, abs(l_ikko[i][0] - l_niko[j][0]) + abs(l_ikko[i][1] - l_niko[j][1]))




print(d_min -1)