void printCommon(Node a, Node b) {
	    Stack<Node> stackA = new Stack<>();
	    Stack<Node> stackB = new Stack<>();
	    Node currentA = a;
	    Node currentB = b;

	   while ((!stackA.isEmpty() || currentA != null) && (!stackB.isEmpty() || currentB != null)) {
	       if (currentA != null) {
	           stackA.push(currentA);
	           currentA = currentA.left;
	       } else if (currentB != null) {
	           stackB.push(currentB);
	           currentB = currentB.left;
	       } else if (!stackA.isEmpty() && !stackB.isEmpty()) {
	           currentA = stackA.pop();
	           currentB = stackB.pop();

	           if (currentA.data == currentB.data) {
	               System.out.print(currentA.data + " ");
	               currentA = currentA.right;
	               currentB = currentB.right;
	           } else if (currentA.data < currentB.data) {
	               currentA = currentA.right;
	               stackB.push(currentB);
	               currentB = null;
	           } else if (currentA.data > currentB.data) {
	               currentB = currentB.right;
	               stackA.push(currentA);
	               currentA = null;
	           }
	       }
	   }
    }