21
[1: 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
           18. 19. 20. ]
[1: 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
           0. 0. 0. ]
20
[1:[1: 1 2] 
          [1: 2 3] 
          [1: 3 4]
          [1: 4 5]
          [1: 5 6]
          [1: 6 7]
          [1: 7 8]
          [1: 8 9]
          [1: 9 10]
          [1: 10 11]
          [1: 11 12]
          [1: 12 13]
          [1: 13 14]
          [1: 14 15]
          [1: 15 16]
          [1: 16 17]
          [1: 17 18]
          [1: 18 19]
          [1: 19 20]
          [1: 20 21]]
22
[1:[1: 1 1] 
          [1: 1 2] 
          [1: 2 2]
          [1: 3 2]
          [1: 4 2]
          [1: 5 2]
          [1: 6 2]
          [1: 7 2]
          [1: 8 2]
          [1: 9 2]
          [1: 10 2]
          [1: 11 2]
          [1: 12 2]
          [1: 13 2]
          [1: 14 2]
          [1: 15 2]
          [1: 16 2]
          [1: 17 2]
          [1: 18 2]
          [1: 19 2]
          [1: 20 2]
          [1: 21 2]
]
1
[1: [1: 21 1]]
[1: 2.0]
