MathDB
Circle and Arcs

Source: Iran Second Round 2015 - Problem 5 day 2

May 8, 2015
combinatoricsIran

Problem Statement

A circle is divided into 2n2n equal by 2n2n points. Ali draws n+1n+1 arcs, of length 1,2,,n+11,2,\ldots,n+1. Prove that we can find two arcs, such that one of them is inside in the other one.