using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var containerData = new List<int>(){

            1,

            2,

            3,

            4,

            5

        };

        var activeAndPruneIds = new List<int>(){

            1,

            2,

            3

        };

        var newRequests = containerData.Where(item => !activeAndPruneIds.Contains(item)).ToList();

        foreach(var i in newRequests)

        {

            Console.WriteLine(i);

        }

    }

}