201 people from 5 countries, in each group of 6 at least 2 have same age
Source: Spanish Mathematical Olympiad 1993 P1
August 1, 2018
combinatorics
Problem Statement
There is a reunion of people from different countries. It is known that in each group of people, at least two have the same age. Show that there must be at least people with the same country, age and sex.