h, w = map(int, input().split())

s = [input() for _ in range(h)]

ans = 'No'

for i in range(1, h-1):
    for j in range(1, w-1):
        if s[i][j] == '#' and (s[i-1][j] == '#' or s[i+1][j] == '#' or s[i][j-1] == '#' or s[i][j+1] == '#'):
            ans = 'Yes'

print(ans)
