## https://yukicoder.me/problems/no/2412

from collections import deque

def bfs(H, W, cum_s_array):
    passed = [[False] * (W - 2) for _ in range(H - 2)]
    passed[0][0] = True

    queue = deque()
    queue.append((0, 0))
    while len(queue) > 0:
        h, w = queue.popleft()

        for dh, dw in ((1, 0), (-1, 0), (0, 1), (0, -1)):
            new_h = dh + h
            new_w = dw + w
            if 0 <= new_h < H - 2 and 0 <= new_w < W - 2:
                if cum_s_array[new_h + 3][new_w + 3] - cum_s_array[new_h][new_w + 3] - cum_s_array[new_h + 3][new_w] + cum_s_array[new_h][new_w] == 0:
                    if not passed[new_h][new_w]:
                        passed[new_h][new_w] = True
                        queue.append((new_h, new_w))
    
    return passed[-1][-1]


def reachable(H, W, s_array):
    # 累積和計算
    cum_s_array = [[0] * (W + 1) for _ in range(H + 1)]
    for h in range(H):
        cum_row = 0
        for w in range(W):
            cum_row += s_array[h][w]
            cum_s_array[h + 1][w + 1] = cum_row + cum_s_array[h][w + 1]

    # BFSによる探索
    return bfs(H, W, cum_s_array)


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

    # 迷路のベースを作成
    s_array = []
    for s in S:
        row = []
        for i in range(len(s)):
            if s[i] == "#":
                row.append(1)
            else:
                row.append(0)
        s_array.append(row)
    
    if not reachable(H, W, s_array):
        print(0)
        return
    
    def forbidden(h, w):
        if 0 <= h < 3 and 0 <= w < 3:
            return True
        if H - 3 <= h < H and W - 3 <= w < W:
            return True
        return False

    for h in range(H):
        for w in range(W):
            if S[h][w] == ".":
                if not forbidden(h, w):
                    s_array[h][w] = 1
                    if not reachable(H, W, s_array):
                        print(1)
                        return

                s_array[h][w] = 0
    
    print(2)





if __name__ == '__main__':
    main()