Problem

Source: Tuymaada 2022 Junior P-4

Tags: graph theory, Coloring



Several $good$ points, several $bad$ points and several segments are drawn in the plane. Each segment connects a $good$ point and a $bad$ one; at most $100$ segments begin at each point. We have paint of $200$ colors. One half of each segment is painted with one of these colors, and the other half with another one. Is it always possible to do it so that every two segments with common end are painted with four different colors? (M. Qi, X. Zhang)