Educational Codeforces Round 55 (Rated for Div. 2)

 Educational Codeforces Round 55 (Rated for Div. 2)

题解明天在献上吧，哇咔咔，困啊............

题目一览表	来源	考察知识点	完成时间
A　　Vasya and Book	cf	找规律	2018.11.30
B　　Vova and Trophies	cf	思维？？	2018.11.30
C　　Multi-Subject Competition	cf	贪心？？	2018.11.30