Mr. Heath owns a game store. He offers workshops where students learn about different kinds of games and how to design their own games.

Sia designs a board game in which a card is drawn on each turn.

• A blue card means move forward 4 squares.
• A red card means move back 6 squares.

Sia begins at 0. She draws a blue card on each of her first three turns.
Then Sia draws only red cards and ends up back at 0. How many red cards did Sia draw?