# Complete graphs 1

**Discrete Mathematics**Level 3

Each of the edges of a complete graph with 9 vertices is coloured either blue or red. There either there exist x vertices with all the edges connecting them blue, or y vertices with all the edges connecting them red.

Find the maximum value of x + y

Details - In the mathematical field of graph theory, a complete graph is a simple undirected graph in which every pair of distinct vertices is connected by a unique edge.