1 
P1  Hamming Distance Sum 
Codeforces 
Codeforces Round #336 (Div. 2) 
2 
P2  Simple Base Conversion 
URI 

3 
P3  Lucky Numbers 
Codeforces 
Experimental Educational Round: VolBIT Formulas Blitz 
4 
P4  Pasha and Stick 
Codeforces 
Codeforces Round #337 (Div. 2) 
5 
P5  Joty and Chocolate 
Codeforces 
Educational Codeforces Round 13 
6 
P6  Olesya and Rodion 
Codeforces 
Codeforces Round #324 (Div. 2) 
7 
P7  The number of positions 
Codeforces 
Codeforces Beta Round #92 (Div. 2 Only) 
8 
P8  The World is a Theatre 
Codeforces 
Codeforces Beta Round #95 (Div. 2) 
9 
P9  Divide by three, multiply by two 
Codeforces 
Codeforces Round #479 (Div. 3) 
10 
P10  Godsend 
Codeforces 
Codeforces Round #429 (Div. 2) 
11 
P11  Almost Identity Permutations 
Codeforces 
Educational Codeforces Round 32 
12 
P12  Spider Man 
Codeforces 
Codeforces Round #366 (Div. 2) 
13 
P13  Conan and Agasa play a Card Game 
Codeforces 
Codecraft18 and Codeforces Round #458 (Div. 1 + Div. 2, combined) 