Participants at an Olympiad stand in a circle
Source: Russian TST 2016, Day 10 P2 (Group A), P3 (Group B)
April 19, 2023
combinatorics
Problem Statement
An Olympiad has 99 tasks. Several participants of the Olympiad are standing in a circle. They all solved different sets of tasks. Any two participants standing side by side do not have a common solved problem, but have a common unsolved one. Prove that the number of participants in the circle does not exceed