2014 China Second Round Olympiad Second Part Problem 4
Source: 2014 China Second Round Olympiad
August 5, 2015
number theory
Problem Statement
Let x1,x2,…,x2014 be integers among which no two are congurent modulo 2014. Let y1,y2,…,y2014 be integers among which no two are congurent modulo 2014. Prove that one can rearrange y1,y2,…,y2014 to z1,z2,…,z2014, so that among x1+z1,x2+z2,…,x2014+z2014 no two are congurent modulo 4028.