1 var 1 index 
2 var 1 valid
3 array 1 1

4 one 1
5 add 1 1 4
6 next 1 1 5 

8 next 1 2 4

9 zero 1
10 write 1 1 3 1 9
11 anext 1 1 3 10 

12 var 1 lambda
13 read 1 3 12 
14 ne 1 13 9
15 eq 1 1 9 
16 and 1 14 15
17 and 1 2 16
18 root 1 17