public static void main(String[] args) { 
        RedBlackBST<String, Integer> st = new RedBlackBST<String, Integer>();
        int i = 0;
        System.out.println("Digite um no");
      Scanner key = new Scanner(System.in);
        do {
        	System.out.println("Digite um no");
        	if(!key.equals(null)) {
        		st.put(key.nextLine(), i);
        		 }
        }while(!key.equals(null));
        for (String s : st.keys())
			System.out.println(s + " " + st.get(s));
		System.out.println();
    }