45 in alumni meeting - All-Russian MO 2003 Regional (R4) 10.3
Source:
September 17, 2024
combinatorics
Problem Statement
people came to the alumni meeting. It turned out that any two of them, having the same number of acquaintances among those who came, don't know each other. What is the greatest number of pairs of acquaintances that could to be among those participating in the meeting?