H, W = map(int, input().split())
campus = list(input() for i in range(W))


def check_around(x, y):
    if 0 < y and campus[y - 1][x] == '#':
        return True
    elif 0 < x and campus[y][x - 1] == '#':
        return True
    elif x < W - 1 and campus[y][x + 1] == '#':
        return True
    elif y < H - 1 and campus[y + 1][x] == '#':
        return True
    return False


can = True
for y in range(H):
    for x in range(W):
        if campus[y][x] == '#':
            can = check_around(x, y)
            if not can:
                print('No')
                exit()
print('Yes')

