MathDB

2

Part of 2015 Turkey Junior National Olympiad

Problems(1)

20 paintings have a common color but not all paintings do

Source: 2015 Turkey Junior National Olympiad P2

12/7/2015
In an exhibition there are 100100 paintings each of which is made with exactly kk colors. Find the minimum possible value of kk if any 2020 paintings have a common color but there is no color that is used in all paintings.
combinatorics