Codeforces Beta Round #54 (Div. 2) A. Chat room

01-30

Codeforces Round #197 (Div. 2) A. Helpful Maths

01-29

Codeforces Round #143 (Div. 2) A. Team

01-24

Codeforces Round #310 (Div. 2) A. Case of the Zeros and Ones

01-15

Codeforces Beta Round #47 A. Domino piling

01-14