输出和其它几道经验题一样是：

Case #1:
6: 1

Case #2:
15: 1
16: 1
17: 1
19: 1
21: 1

Case #3:
6: 1
7: 1
8: 2
9: 3
10: 4
11: 5
12: 7
13: 8
14: 9
15: 10
16: 10
17: 10
18: 10
19: 9
20: 8
21: 7
22: 5
23: 4
24: 3
25: 2
26: 1
27: 1

虽然可能pe一次就发现了/wul 。