Problem 7 of Third round
Source: VI International Festival of Young Mathematicians Sozopol, Theme for 10-12 grade
December 24, 2019
number theoryset theorysums
Problem Statement
Determine the greatest natural number , such that for each set of 2015 different integers there exist 2 subsets of (possible to be with 1 element and not necessarily non-intersecting) each of which has a sum of its elements divisible by .