from collections import deque
import sys

input = sys.stdin.readline
H, W = map(int, input().split())
C = [input().strip() for _ in range(H)]

HH, WW = 2 * H - 1, 2 * W - 1

def ok(x, y):
    return 0 <= x < HH and 0 <= y < WW and not (
        x % 2 == 0 and y % 2 == 0 and C[x // 2][y // 2] == "#"
    )

dist = [[-1] * WW for _ in range(HH)]
dist[0][0] = 0
q = deque([(0, 0)])

while q:
    x, y = q.popleft()

    ns = []
    for dx, dy in ((1, 0), (-1, 0), (0, 1), (0, -1)):
        ns.append((x + dx, y + dy))

    if x % 2 == 0 and y % 2 == 0:
        ns += [(x + 2, y), (x - 2, y), (x, y + 2), (x, y - 2)]
    elif x % 2 == 1 and y % 2 == 0:
        ns += [(x, y + 2), (x, y - 2)]
    elif x % 2 == 0 and y % 2 == 1:
        ns += [(x + 2, y), (x - 2, y)]

    for nx, ny in ns:
        if ok(nx, ny) and dist[nx][ny] < 0:
            dist[nx][ny] = dist[x][y] + 1
            q.append((nx, ny))

print(dist[-1][-1])