using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        List<Transaction> list = new List<Transaction>();

        var distintctList = list.Select(p=>p.ReferNumber).Distinct();

        foreach(var item in distintctList){

        Console.WriteLine(isValidTransaction(list.Where(p=>p.ReferNumber == item).ToList()));

        }

    }

    public static bool isValidTransaction(List<Transaction> list){

        var length = list.Count();

        for(int i =0; i< length; i++){

            //on every even position there should be create 

            if(i%2 == 0 && list[i].Value != "Create"){

            return false;

            }

            // on every odd position there should be Void operation.

            else if(i%2 ==1 && list[i].Value!="Void"){

            return false;

            }

        }

        return true;

    }

}

​

public class Transaction{

​

​

public int Index{get;set;}

​

public String Value{get;set;}

​

 public int ReferNumber{get;set;}

​

​

}

​