private void visitNode(BinaryNode<K, V, W> node, String s) {
		 if(node.left != null){
			 if(s.equals(node.address)){
				 System.out.println(node.value+", "+" rollnumber: "+node.key);
			 }
			 visitNode(node.left,s);
		 }
		 
		 if(node.right != null) {
			 if(s.equals(node.address)){
				 System.out.println(node.value+", "+" rollnumber: "+node.key);
			 }
			 visitNode(node.right,s);
		 }
		 
		 if(node.left == null && node.right == null) {
			 if(s.equals(node.address)){
				 System.out.println(node.value+", "+" rollnumber: "+node.key);
			 }
		 }
		 
		 
		
	}