using System;

​

public class Program

{

    public static void Main()

    {

        Node node14 = new Node{LeftNode = null, RightNode = null};

        Node node13 = new Node{LeftNode = null, RightNode = null};

        // Node node12 = new Node { LeftNode = null, RightNode = null }; NOTE: This was not present in the image

        Node node11 = new Node{LeftNode = null, RightNode = null};

        Node node10 = new Node{LeftNode = null, RightNode = null};

        Node node9 = new Node{LeftNode = null, RightNode = null};

        Node node8 = new Node{LeftNode = null, RightNode = null};

        Node node7 = new Node{LeftNode = node14, RightNode = null};

        Node node6 = new Node{LeftNode = null, RightNode = node13};

        Node node5 = new Node{LeftNode = node10, RightNode = node11};

        Node node4 = new Node{LeftNode = node8, RightNode = node9};

        Node node3 = new Node{LeftNode = node6, RightNode = node7};

        Node node2 = new Node{LeftNode = node4, RightNode = node5};

        Node node1 = new Node{LeftNode = node2, RightNode = node3};

        int num = getNumChildren(node1);

        Console.WriteLine(num);

    }

​

    public static int getNumChildren(Node left)

    {

        if (left == null)

        {

            return 0;

        }

​

        if (left.LeftNode == null && left.RightNode == null)

        {

            return 1;

        }

​

        return getNumChildren(left.LeftNode) + getNumChildren(left.RightNode) + 1;

    }

}

​

public class Node

{

    public Node LeftNode

    {

        get;

        set;

    }

​

    public Node RightNode

    {

        get;

        set;

    }

}