Problem #PRU-58080

Problemas Matemáticas Discretas Combinatoria Geometría en papel cuadriculado Problemas de pintura Métodos Principio del casillero Principio del casillero (número finito de puntos, líneas, etc.)
 12–13  3.0

Problem

A ream of squared paper is shaded in two colours. Prove that there are two horizontal and two vertical lines, the points of intersection of which are shaded in the same colour.