Benny has $$4$$ blue marbles, $$3$$ yellow marbles and $$1$$ red marble in his pocket. Without looking into his pocket, how many marbles must be taken out from his pocket to be sure he gets $$3$$ marbles of the same colour? 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations Overseas Competition->Knowledge Point->Combinatorics->Pigeonhole Principle->Worst Case in Pigeonhole Principle Problems