1 start
1 get b
2 get b
2 get a
3 get a
3 conv c
4 conv c
4 conv b
5 conv b
5 111
6 111
7 done with first
6 get b
8 get b
7 get b
9 get b
8 conv c
10 conv c
9 conv b
11 conv b
10 conv b
12 conv b