2
1 uses the screen of 4 to go to the basket, and recieves the ball from 3 to score.
At the same time 2 fills the guard position (defense in case of a turnover, and pass option for 3). We used to let 2 fill the spot after 1 had passed the free throw line.
If 3 can't get the ball to 1, 3 passes the ball to 2 who can then pass it to 1 which took the 2 spot and start one of the weakside options.
3 should also not forget to look and feed the centers.