Problem

Source: Ukrainian Mathematical Olympiad 2024. Day 2, Problem 11.7

Tags: combinatorial geometry, combinatorics



You are given $2024$ yellow and $2024$ blue points on the plane, and no three of the points are on the same line. We call a pair of nonnegative integers $(a, b)$ good if there exists a half-plane with exactly $a$ yellow and $b$ blue points. Find the smallest possible number of good pairs. The points that lie on the line that is the boundary of the half-plane are considered to be outside the half-plane. Proposed by Anton Trygub