/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */

class Solution {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        TreeNode ancerstor = root;
        while(true){
            if(ancerstor.val > p.val && ancerstor.val > q.val)
                ancerstor = ancerstor.left;
            else if(ancerstor.val < p.val && ancerstor.val < q.val)
                ancerstor = ancerstor.right;
            else    
                break;
        }
        return ancerstor;
    }
}