from collections import deque


def canReach(H, W, Ss):
    grid = [[False for _ in range(W - 2)] for _ in range(H - 2)]
    for h in range(1, H - 1):
        for w in range(1, W - 1):
            grid[h - 1][w - 1] = True
            for dh in range(-1, 2):
                for dw in range(-1, 2):
                    if Ss[h + dh][w + dw] == "#":
                        grid[h - 1][w - 1] = False

    # 0,0からH-3,W-3までの経路があるか
    adj = [[[] for _ in range(W - 2)] for _ in range(H - 2)]
    for h in range(H - 2):
        for w in range(W - 2):
            if not grid[h][w]:
                continue
            for dh in range(-1, 2):
                for dw in range(-1, 2):
                    if dh == 0 and dw == 0:
                        continue
                    if (
                        0 <= h + dh < H - 2
                        and 0 <= w + dw < W - 2
                        and grid[h + dh][w + dw]
                    ):
                        adj[h][w].append((h + dh, w + dw))

    q = deque([(0, 0)])
    visited = [[False for _ in range(W - 2)] for _ in range(H - 2)]
    visited[0][0] = True
    while q:
        h, w = q.popleft()
        for nh, nw in adj[h][w]:
            if not visited[nh][nw]:
                visited[nh][nw] = True
                q.append((nh, nw))

    return visited[H - 3][W - 3]


def main():
    H, W = map(int, input().split())
    assert 6 <= H <= 500
    assert 6 <= W <= 500
    Ss = []
    for _ in range(H):
        S = input().strip()
        assert len(S) == W
        for c in S:
            assert c == "." or c == "#"
        Ss.append(S)

    for i in range(3):
        for j in range(3):
            assert Ss[i][j] == "."
    for i in range(H - 3, H):
        for j in range(W - 3, W):
            assert Ss[i][j] == "."

    ans = 2
    if not canReach(H, W, Ss):
        ans = 0
    else:
        for h in range(H):
            for w in range(W):
                if h < 3 and w < 3:
                    continue
                if h >= H - 3 and w >= W - 3:
                    continue
                if Ss[h][w] == "#":
                    continue
                Ss[h] = Ss[h][:w] + "#" + Ss[h][w + 1 :]
                if not canReach(H, W, Ss):
                    ans = 1
                Ss[h] = Ss[h][:w] + "." + Ss[h][w + 1 :]

    print(ans)


if __name__ == "__main__":
    main()