As Inefficient As Possible
Source: Indonesia RMO 2022, Essay No 5 (Modified from Mathematical Excalibur 510)
August 24, 2022
IndonesiaRMO2022mathematicalexcaliburcombinatorics
Problem Statement
Numbers to are written on a board. A "move" is a procedure of picking two numbers on the board such that , then erasing and to be replaced with and . Determine the maximum possible number of moves that can be done on the board.