h, w = map(int, input().split())
s = ["."+input()+"." for _ in range(h)]
s = ["."*(w+2)]+s+["."*(w+2)]
flag = False

for i in range(h):
    for j in range(w):
        if s[i][j] == '#':
            if s[i-1][j] == '.' and s[i+1][j] == '.' and s[i][j-1] == '.' and s[i][j+1] == '.':
                flag = True

if flag:
    print('Yes')
else:
    print('No')
