using System;

using System.Collections.Generic;

using System.Linq;

​

public class EmployeeTechnicalExposure{

    public int ExposureId {get;set;}

    public string Employee {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        List<EmployeeTechnicalExposure> existingTechincalExposuresState =  new List<EmployeeTechnicalExposure>(){

            new EmployeeTechnicalExposure{ExposureId = 1,Employee = "Dallin"},

            new EmployeeTechnicalExposure{ExposureId = 2,Employee = "Dallin"},

            new EmployeeTechnicalExposure{ExposureId = 3,Employee = "Dallin"}

        };

        List<EmployeeTechnicalExposure> newTechincalExposuresState =  new List<EmployeeTechnicalExposure>(){

​

            new EmployeeTechnicalExposure{ExposureId = 3,Employee = "Dallin"},

            new EmployeeTechnicalExposure{ExposureId = 4,Employee = "Dallin"}

        };

        // 1 & 2 was removed, 4 was added

        List<int> technicalExposureIdToRemove = existingTechincalExposuresState.Select(te => te.ExposureId).Where(oldStateId => !newTechincalExposuresState.Select(te => te.ExposureId).Contains(oldStateId)).ToList();

        Console.WriteLine("To Remove:");

        technicalExposureIdToRemove.ForEach(id => Console.WriteLine(id));

        List<int> technicalExposureIdToAdd = newTechincalExposuresState.Select(te => te.ExposureId).Where(newStateId => !existingTechincalExposuresState.Select(te => te.ExposureId).Contains(newStateId)).ToList();    

        Console.WriteLine("To Add:");

        technicalExposureIdToAdd.ForEach(id => Console.WriteLine(id));

    }

}