CGMO 2011 Problem 4

A tennis tournament has $n>2$ players and any two players play one game against each other (ties are not allowed). After the game these players can be arranged in a circle, such that for any three players $A,B,C$ , if $A,B$ are adjacent on the circle, then at least one of $A,B$ won against $C$ . Find all possible values for $n$ .