import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @param p int整型 
     * @param q int整型 
     * @return int整型
     */
    public int lowestCommonAncestor (TreeNode root, int p, int q) {
        // write code here
        int ans = root.val;
        while (true) {
            if (p < root.val && q < root.val) {
                root = root.left;
            } else if (p > root.val && q > root.val) {
                root = root.right;
            } else {
                ans = root.val;
                break;
            }
        }
        return ans;
    }
}