Problem

Source: 2013 Baltic Way, Problem 9

Tags: combinatorial geometry, combinatorics unsolved, combinatorics



In a country there are $2014$ airports, no three of them lying on a line. Two airports are connected by a direct flight if and only if the line passing through them divides the country in two parts, each with $1006$ airports in it. Show that there are no two airports such that one can travel from the first to the second, visiting each of the $2014$ airports exactly once.