Liars and Truth-Sayers around a table
Source: 2023 Israel National Olympiad P1
December 16, 2022
combinatoricsnational olympiad
Problem Statement
2000 people are sitting around a round table. Each one of them is either a truth-sayer (who always tells the truth) or a liar (who always lies). Each person said: "At least two of the three people next to me to the right are liars". How many truth-sayers are there in the circle?