#!/usr/bin/env python
# -*- coding: utf-8 -*-

def dfs(x,y,c):
    Map[y][x] = str(c)
    dxdy = [(1,0),(-1,0),(0,1),(0,-1)]
    for dx,dy in dxdy:
        if Map[y + dy][x + dx] == '.':
            dfs(x + dx,y + dy,c)

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

count = 0
for i in range(H):
    for j in range(W):
        if Map[i][j] == '.':
            dfs(j,i,count)
            count += 1

min_dist = 10**8
for i in range(H):
    for j in range(W):
        if Map[i][j] == '0':
            for k in range(H):
                for l in range(W):
                    if Map[k][l] == '1':
                        min_dist = min(min_dist,abs(i-k) + abs(j-l))

print(min_dist-1)