What to put on the door of a barber shop?

Post some appropriate slogans.

The slogan is as follows:

1. There are only people who are here to play the game, and there should be no one who is scratching their heads here.

2. In comes the long-haired student, and out comes the white-faced scholar.

3. When you come in, you look old with a long and messy beard, but when you go out, you look young and have a clear face.

4. Leave your hair and take away your face.