#############################################################

import sys
sys.setrecursionlimit(10**7)

from heapq import heappop,heappush
from collections import deque,defaultdict,Counter
from bisect import bisect_left, bisect_right
from itertools import product,combinations,permutations
from math import sin,cos
#from math import isqrt #DO NOT USE PyPy

ipt = sys.stdin.readline
iin = lambda :int(ipt())
lmin = lambda :list(map(int,ipt().split()))

#############################################################

H,W = lmin()
T = [list(input()) for _ in range(H)]

st = [(1,1)]


d = []
for i in range(-1,2):
    for j in range(-1,2):
        if i|j == 0:
            continue
        d.append((i,j))

def func(S):
    st = [(1,1)]
    visited = [[0]*W for _ in range(H)]

    while st:
        i,j = st.pop()
        if i == H-2 and j == W-2:
            return True
        for di,dj in d:
            ni = di+i
            nj = dj+j
            if 1<=ni<H-1 and 1<=nj<W-1:
                if visited[ni][nj]:
                    continue
                visited[ni][nj] = 1
                g = 0
                for ii in range(-1,2):
                    for jj in range(-1,2):
                        if S[ni+ii][nj+jj] == "#":
                            g = 1
                if g == 0:
                    st.append((ni,nj))

    return False

if not func(T):
    print(0)
    exit()

for i in range(H):
    for j in range(W):
        if i <= 2 and j <= 2:
            continue
        if i >= H-3 and j >= W-3:
            continue
        if T[i][j] == ".":
            T[i][j] = "#"
            if not func(T):
                print(1)
                exit()
            T[i][j] = "."

print(2)