We are given a 4×4 square, consisting of 16 squares with side length of 1. Every 1×1 square inside the square has a non-negative integer entry such that the sum of any five squares that can be covered with the figures down below (the figures can be moved and rotated) equals 5. What is the greatest number of different numbers that can be used to cover the square? JMMOJunior2016Macedoniacombinatorics