40求调

rp = [
    lambda x, y: (x, y+1),
    lambda x, y: (x-1, y),
    lambda x, y: (x, y-1),
    lambda x, y: (x+1, y)
]

def yidong():
    x = p[-1][0]
    y = p[-1][1]
    for o in rp:
        l = o(x, y)
        l = list(l)
        if l in q:
            continue
        else:
            a = l[0]
            b = l[1]
            if 0 <= a < n and 0 <= b < m:
                if mo[a][b] == '.':
                    q.append(l)
                    p.append(l)
                    break
                else:
                    continue

    else:
        p.pop()

mo = []
ol = []
q = []  # 标记
p = [[0, 0]]  # 路线
n, m = map(int, input().split())
for i in range(n):
    j = input()
    g = [a for a in j]
    mo.append(g)
while p[-1] != [n-1, m-1]:
    yidong()
    if len(p) < 2:
        print('No')
        break
else:
    print('Yes')