This website contains problems from math contests. Problems and corresponding tags were obtained from the Art of Problem Solving website.

Tags were heavily modified to better represent problems.

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Found problems: 2

2015 Junior Regional Olympiad - FBH, 5
Tags: disjoint , set
Prove that for every parititon of set $X=\{1,2,...,9\}$ on two disjoint sets at least one of them contains three elements such that sum of some two of them is equal to third

2004 Regional Olympiad - Republic of Srpska, 4
Tags: set , combinatorics , subset , division , disjoint
Set $S=\{1,2,...,n\}$ is firstly divided on $m$ disjoint nonempty subsets, and then on $m^2$ disjoint nonempty subsets. Prove that some $m$ elements of set $S$ were after first division in same set, and after the second division were in $m$ different sets