Codeforces Round 450 Div2 B.Jzzhu and Sequences

11-29

Codeforces Round #132(Div2) A.Bicycle Chain

11-10

Codeforces Round #517(Div2) A.Golden Plate

10-21

Codeforces Round #512(Div2) B.Vasya and Cornfield

10-17