def main():
    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")
                return
    print("Yes")

main()