using System;

 using System.Collections;

 using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Run();

    }

        public static void Run()

         {

             var ls = new List<int>(){

                 1,3,5,7,9,11

             };

             var ls2 = new List<int>(){

                 2,4,6,8,10

             };

             var lsContainer = new AdditionContainer<List<int>,int>(ls);

             var ls2Container = new AdditionContainer<List<int>,int>(ls2); 

             var finalAnsower =   lsContainer +ls2Container;

             finalAnsower.List.ForEach(f=>Console.WriteLine(f) );

​

​

         }

}

​

​

public class AdditionContainer<TList,T>

     where TList:List<T>

     {

         public TList List;

         public AdditionContainer(TList list )

         {

               List=list;   

         }

​

         public static AdditionContainer<TList,T> operator +(AdditionContainer<TList,T> a, AdditionContainer<TList,T> b)

         {

               b.List.ForEach(l =>{

                  if(!a.List.Contains(l))

                  {

                     a.List.Add(l);  

                  }

               });

               return a;

         }       

     }