MathDB
Cono Sur Olympiad 2013, Problem 4

Source:

August 22, 2014
inductioncombinatorics proposedcombinatorics

Problem Statement

Let MM be the set of all integers from 11 to 20132013. Each subset of MM is given one of kk available colors, with the only condition that if the union of two different subsets AA and BB is MM, then AA and BB are given different colors. What is the least possible value of kk?