1 
P1  Little Girl and Maximum Sum 
Codeforces 
Codeforces Round #169 (Div. 2) 
2 
P2  Xenia and Bit Operations 
Codeforces 
Codeforces Round #197 (Div. 2) 
3 
P3  Knight Tournament 
Codeforces 
Codeforces Round #207 (Div. 1) & Codeforces Round #207 (Div. 2) 
4 
P4  Dima and Staircase 
Codeforces 
Codeforces Round #167 (Div. 2) & Codeforces Round #167 (Div. 1) 
5 
P5  Pashmak and Parmida's problem 
Codeforces 
Codeforces Round #261 (Div. 2) 
6 
P6  Enemy is weak 
Codeforces 
Codeforces Beta Round #57 (Div. 2) 
7 
P7  Exposition 
Codeforces 
Codeforces Beta Round #6 (Div. 2 Only) 
8 
P8  Nested Segments 
Codeforces 
Educational Codeforces Round 10 
9 
P9  Horrible Queries 
SPOJ 

10 
P10  Multiples of 3 
SPOJ 

11 
P11  Sereja and Brackets 
Codeforces 
Codeforces Round #223 (Div. 1) & Codeforces Round #223 (Div. 2) 
12 
P12  Dquery 
SPOJ 

13 
P13  SUM and REPLACE 
Codeforces 
Educational Codeforces Round 37 (Rated for Div. 2) 