2 var 1 valid
3 array 1 1
4 one 1

8 next 1 2 4

9 zero 1
10 write 1 1 3 2 9
11 anext 1 1 3 10 

13 read 1 3 9 
14 ne 1 13 9
15 and 1 2 14
16 root 1 15