What if we connect the cities of Graphland?
Source: Tuymaada 2000, day 2, problem 2.
April 30, 2007
inductioncombinatorics proposedcombinatorics
Problem Statement
There are 2000 cities in Graphland; some of them are connected by roads.
For every city the number of roads going from it is counted. It is known that there are exactly two equal numbers among all the numbers obtained. What can be these numbers?