import sys
import pypyjit
import itertools
import heapq
import math
from collections import deque, defaultdict
import bisect

input = sys.stdin.readline
sys.setrecursionlimit(10 ** 6)
pypyjit.set_param('max_unroll_recursion=-1')


def index_lt(a, x):
    'return largest index s.t. A[i] < x or -1 if it does not exist'
    return bisect.bisect_left(a, x) - 1


def index_le(a, x):
    'return largest index s.t. A[i] <= x or -1 if it does not exist'
    return bisect.bisect_right(a, x) - 1


def index_gt(a, x):
    'return smallest index s.t. A[i] > x or len(a) if it does not exist'
    return bisect.bisect_right(a, x)


def index_ge(a, x):
    'return smallest index s.t. A[i] >= x or len(a) if it does not exist'
    return bisect.bisect_left(a, x)


W, H = map(int, input().split())
C = [input()[:-1] for _ in range(H)]

for i in range(H):
    for j in range(W):
        if C[i][j] == '.':
            rs, cs = i, j
            break
INF = 1 << 30
cost = [[INF for _ in range(W)] for _ in range(H)]
cost[rs][cs] = 0
dq = deque([(rs, cs)])
while len(dq) > 0:
    r, c = dq.popleft()
    darr = [(1, 0), (0, 1), (-1, 0), (0, -1)]
    for dr, dc in darr:
        ar, ac = r + dr, c + dc
        if ar < 0 or ar > H - 1 or ac < 0 or ac > W - 1:
            continue
        if C[ar][ac] == '#':
            if cost[ar][ac] > cost[r][c] + 1:
                cost[ar][ac] = cost[r][c] + 1
                dq.append((ar, ac))
        else:
            if cost[ar][ac] > cost[r][c]:
                cost[ar][ac] = cost[r][c]
                dq.appendleft((ar, ac))
ans = INF
for i in range(H):
    for j in range(W):
        if C[i][j] == '#' or cost[i][j] == 0:
            continue
        ans = min(ans, cost[i][j])
print(ans)