1c2b3d4b
1-5 CBDBC
6-10 DDBAA
11-15 AACCB
16-20 BBABB
21-25 BBACD
26-30 CCABD
31-35 DADBA
36-40 CCDDA
41-45 DAAAA
46-50 ADABB
Wang Na
2021.3.25