using System;

using System.Collections;

​

public class Program

{

    public Node root;

    public Hashtable table = new Hashtable();

    public static int element = 0;

    public class Node

    {

        public int data;

        public Node left;

        public Node right;

        public Node(int d)

        {

            data = d;

            left = right = null;

        }

    }

​

    public void Inorder(Node root)

    {

        if (root == null)

        {

            return;

        }

​

        Inorder(root.left);

        table.Add(element, root.data);

        element++;

        Inorder(root.right);

    }

    public void CreateArray()

    {

        int[] array=new int[element];

        int count=0;

        foreach(var item in table.Keys)

        {

        array[count]=Convert.ToInt32(table[item]);

        count++;    

        }

        Alternamesum(array);

    }

    public void Alternamesum(int[] elementarray)

    {

        int sum=0;

        int maxsum=int.MinValue;

        for(int i=0;i<elementarray.Length;i++)      

        {

            sum=sum+elementarray[i];

            for(int j=i+2;j<elementarray.Length;j=j+2)

            {

                sum=sum+elementarray[j];

            }

            if(sum>maxsum)

            {

            maxsum=sum; 

            }

            sum=0;

        }

        Console.WriteLine(maxsum);

    }

​

    public static void Main()

    {

        Program tree = new Program();

        tree.root = new Node(1);

        tree.root.left = new Node(2);

        tree.root.right = new Node(3);

        tree.root.left.left = new Node(1);

        tree.root.right.left = new Node(4);

        tree.root.right.right = new Node(5);

        tree.Inorder(tree.root);

        tree.CreateArray();

    }

}