using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class Item

    {

        public int Id {get;set;}

    }

    public static void Main()

    {

        var master = (new []{ 1, 2, 3, 4, 5}).Select(x => new Item {Id = x});

        var update  = (new []{ 1, 3, 5}).Select(x => new Item {Id = x});

        master = master.Join(update.Select(x => x.Id), o => o.Id, id => id, (o, id) => o);

        foreach (var item in master)

        {

            Console.WriteLine(item.Id);

        }

    }

}