public int size(int niveau){
		int size = 0;
		switch(niveau){
			case 1:
				size = beginner.size();
				break;
			case 2:
				size = intermediate.size();
				break;
			case 3:
				size = advanced.size();
				break;
			case 4:
				size = expert.size();
				break;
			case 5:
				size = grandmaster.size();
				break;
			default:
				System.out.println("ERROR ! size = 0 !");					
		}
		return size;
	}