static public void InOrderTraverse_Pro(Tree root) {
		
		Stack<Tree> stack = new Stack<Tree>();
		Tree curr = root;
		while(curr != null || !stack.empty()) {
			if(curr != null) {
				stack.push(curr);
				curr = curr.lc;
			}
			else {
				Tree tmp = stack.pop();
				System.out.print(tmp.data + " ");
				curr = tmp.rc;
			}
		}
	}