No more than 9 stories - Iran First Round 2018, P11
Source:
March 7, 2021
combinatorics
Problem Statement
Based on a city's rules, the buildings of a street may not have more than stories. Moreover, if the number of stories of two buildings is the same, no matter how far they are from each other, there must be a building with a higher number of stories between them. What is the maximum number of buildings that can be built on one side of a street in this city?