public static void CC1712(){//Hash. PASS
		int n=10;
		Hashtable<Integer, Boolean> table = new Hashtable<Integer, Boolean>();
		int arr[]={2, 4, 6, 1, 3, 2, 5, 9, 3, 5};
		for (int i=0; i<10; ++i){
			table.put(arr[i], true);
		}
		for (int i=0; i<10; ++i){
			if (table.containsKey(n-arr[i])){
				System.out.println("There is a pair " + i + " and " + (n-i));
			}
		}
	}