H, W = map(int, input().split())
S = []
S.append('.' * (H + 2))
S.extend(['.' + input() + '.' for _ in range(H)])
S.append('.' * (H + 2))

for y in range(1, H + 1):
    for x in range(1, W + 1):
        if S[y][x] == '#' and \
        set([S[y - 1][x], S[y + 1][x], S[y][x - 1], S[y][x + 1]]) == set('.'):
            print("No")
            quit()
print("Yes")
