PLFA agda exercises
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
[14, 36, 20, 16, 15, 196, 13, 12, 11, 20, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 20, 20, 36, 196]
[14, 18, 17, 16, 15, 392, 13, 12, 11, 20, 9, 11, 7, 6, 5, 4, 3, 2, 1, 0]
[0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 11, 12, 13, 14, 15, 16, 17, 18, 20, 392]