1:in=0+out=1, 1:in=1+out=0, 1:in=1+out=1:

1:in=0+out=2, 1:in=1+out=1, 1:in=2+out=0:

1:in=0+out=2, 2:in=1+out=0:

2:in=0+out=1, 1:in=2+out=0:

3:in=1+out=1: