**i got this answer from the youtube **

import java.io.; import java.util.*;

public class Solution {

public static class Node
{
    public int data ;
    public Node leftNode;
    public Node rightNode;
    public Node(int data)
    {
        this.data = data;
        this.leftNode = null;
        this.rightNode = null;

    }
}


public static Node buildTree(Node root,int data)
{
    if(root == null)
    {
        root = new Node(data);
        return root;
    }

    if(root.data > data)
    {
        root.leftNode = buildTree(root.leftNode, data);
    }
    if(root.data<data)
    {
        root.rightNode = buildTree(root.rightNode, data);
    }
    return root;
}

public static Node lca(Node root,int a,int b)
{
    if(root.data < a && root.data < b)
    {
        return lca(root.rightNode,a,b);
    }
    if(root.data > a && root.data > b)
    {
        return lca(root.leftNode,a,b);
    }
    return root;
}

public static void main(String[] args) {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
    Scanner sc=  new Scanner(System.in);
        Node root = null;
        int n = sc.nextInt();
        int i=0;
        while(i<n)
        {
            i++;
            int inp = sc.nextInt();
            root = buildTree(root, inp);
        }
        int a,b;
        a=sc.nextInt();b=sc.nextInt();
        Node lcaNode = lca(root, a, b);
        System.out.println(lcaNode.data);
        sc.close();


}

}