1 
P1  Watermelon 
Codeforces 
Codeforces Beta Round #4 (Div. 2 Only) 
2 
P2  Trip For Meal 
Codeforces 
Codeforces Round #441 (Div. 2, by Moscow Team Olympiad) 
3 
P3  Fraction 
Codeforces 
Codeforces Round #433 (Div. 2, based on Olympiad of Metropolises) 
4 
P4  Sasha and Sticks 
Codeforces 
Codeforces Round #425 (Div. 2) 
5 
P5  Wizards' Duel 
Codeforces 
Codeforces Round #327 (Div. 2) 
6 
P6  Even, Odd, Positive and Negative 
URI 

7 
P7  Six Odd Numbers 
URI 

8 
P8  Multiples 
URI 

9 
P9  Quadcopter Competition 
Codeforces 
20172018 ACMICPC, NEERC, Southern Subregional Contest (Online Mirror, ACMICPC Rules, Teams Preferred) 
10 
P10  Maxim Buys an Apartment 
Codeforces 
Codeforces Round #433 (Div. 2, based on Olympiad of Metropolises) 