from collections import deque

H, W = map(int, input().split())
S = [input() for _ in range(H)]

def func(h, w):
    if h == 0 or h == H-1 or w == 0 or w == W-1:
        return False
    for dh in range(-1, 2):
        nh = h+dh
        for dw in range(-1, 2):
            nw = w+dw
            if S[nh][nw] == "#":
                return False
    return True

def bfs(a, b):
    visited = [[False]*W for _ in range(H)]
    visited[1][1] = True
    que = deque()
    que.append((1, 1))
    while que:
        h, w = que.popleft()
        for dh in range(-1, 2):
            nh = h+dh
            for dw in range(-1, 2):
                nw = w+dw
                if max(abs(a-nh), abs(b-nw)) <= 1: continue
                if F[nh][nw] and not visited[nh][nw]:
                    visited[nh][nw] = True
                    que.append((nh, nw))
    return visited[H-2][W-2]

F = [[func(h, w) for w in range(W)] for h in range(H)]

if not bfs(-1, -1):
    print(0)
    exit()

flag = False
for i in range(H):
    for j in range(W):
        if max(i, j) <= 2 or H-3 <= i and W-3 <= j:
            continue
        flag |= not bfs(i, j)

print(1 if flag else 2)