Plays with polygon
Source: St Petersburg Olympiad 2011, Grade 9, P7
September 15, 2017
combinatoricsnumber theory
Problem Statement
Sasha and Serg plays next game with -angled regular polygon . In the beggining Sasha set natural numbers in every angle. Then they make turn by turn, first turn is made by Serg. Serg turn is to take two opposite angles and add to its numbers. Sasha turn is to take two neigbour angles and add to its numbers. Serg want to maximize amount of odd numbers. What maximal number of odd numbers can he get no matter how Sasha plays?