import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(1000005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = -1-(-1 << 63)
# md = 10**9+7
md = 998244353

from collections import deque

h, w = LI()
ss = [[(c == "#")*1 for c in SI()] for _ in range(h)]

for i in range(h):
    for j in range(w):
        if ss[i][j] == 1:
            for di, dj in dij:
                ni, nj = i+di, j+dj
                if ni < 0 or nj < 0 or ni >= h or nj >= w: continue
                if ss[ni][nj] == 0: ss[ni][nj] = 2
# p2D(ss)

q = deque()
dist = [[inf]*w for _ in range(h)]
for j in range(w):
    if ss[0][j]:
        q.append((0, j))
        dist[0][j] = 0
for i in range(h):
    if ss[i][w-1]:
        q.append((i, w-1))
        dist[i][w-1] = 0

while q:
    i, j = q.popleft()
    d = dist[i][j]
    for di, dj in dij:
        ni, nj = i+di, j+dj
        if ni < 0 or nj < 0 or ni >= h or nj >= w: continue
        if dist[ni][nj] == inf:
            if d == 0 and ss[ni][nj]:
                dist[ni][nj] = 0
                q.appendleft((ni,nj))
            else:
                dist[ni][nj] = d+1
                q.append((ni, nj))

st = []
for i in range(h):
    if ss[i][0]:
        if dist[i][0] == 0:
            print(0)
            exit()
        if dist[i][0] < 5:
            print(1)
            exit()
        st.append((i, 0))
for j in range(w):
    if ss[h-1][j]:
        if dist[h-1][j] == 0:
            print(0)
            exit()
        if dist[h-1][j] < 5:
            print(1)
            exit()
        st.append((h-1, j))

while st:
    i, j = st.pop()
    for di, dj in dij:
        ni, nj = i+di, j+dj
        if ni < 0 or nj < 0 or ni >= h or nj >= w: continue
        if ss[ni][nj] and dist[ni][nj] != inf:
            if dist[ni][nj] < 5:
                print(1)
                exit()
            dist[ni][nj] = inf
            st.append((ni, nj))

print(2)