import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main
{
    private static class Node
    {
        private Node left;
        private Node right;
        private int value;

        public Node(int value)
        {
            this.value = value;
        }

        public String toString()
        {
            return " Value: " + value + "\n";
        }
    }

    private static void insert(int value, Node root)
    {
        if( value < root.value )
        {
            if( root.left != null )
            {
                insert(value,root.left);
            }
            else
            {
                root.left = new Node(value);
            }
        }
        else
        {
            if( root.right != null )
            {
                insert(value,root.right);
            }
            else
            {
                root.right = new Node(value);
            }
        }
    }
    private static Node populate(int[] values, int n)
    {
        if( n <= 0 )
        {
            return null;
        }
        Node root = new Node(values[0]);
        for( int i =1 ; i < n ; i ++ )
        {
            insert(values[i],root);
        }
        return root;
    }
   public static void main(String[] args) {
       Main man = new Main();
   }

    public static int bstDistance(int[] values, int n, int node1, int node2) {

        Node node = populate(values,n);
        return findDistance(node,node1,node2);
    }
    public static int findDistance(Node root, int n1, int n2) {
        int x = Pathlength(root, n1) - 1;
        int y = Pathlength(root, n2) - 1;
        if( x < 0 || y < 0 )
        {
            return -1;
        }
        int lcaData = findLCA(root, n1, n2).value;
        int lcaDistance = Pathlength(root, lcaData) - 1;
        return (x + y) - 2 * lcaDistance;
    }

    public static int Pathlength(Node root, int n1) {
        if (root != null) {
            int x = 0;
            if ((root.value == n1) || (x = Pathlength(root.left, n1)) > 0
                    || (x = Pathlength(root.right, n1)) > 0) {
                // System.out.println(root.value);
                return x + 1;
            }
            return -1;
        }
        return -1;
    }

    public static Node findLCA(Node root, int n1, int n2) {
        if (root != null) {
            if (root.value == n1 || root.value == n2) {
                return root;
            }
            Node left = findLCA(root.left, n1, n2);
            Node right = findLCA(root.right, n1, n2);

            if (left != null && right != null) {
                return root;
            }
            if (left != null) {
                return left;
            }
            if (right != null) {
                return right;
            }
        }
        return null;
    }


    private void print(Node tree)
    {
        System.out.print(tree);
        System.out.print("left" + tree.left + "");
        System.out.print("right" + tree.right + "");
        if( tree.left != null )
        {
            print(tree.left);
        }

        if( tree.right != null )
        {
            print(tree.right);
        }
    }
        }