using System;

using System.Collections.Generic;

using System.Collections.Immutable;

public class Program

{

    public class TrialClass1

    {

        public readonly IList<int> Trial1;

        public TrialClass1(IList<int> trial1){

            this.Trial1 = trial1;

        }

    }

    public class TrialClass2

    {

        public IReadOnlyList<int> Trial2 {get; set;}

    }

    public static void Main()

    {

        List<int> sampleList1 = new List<int>() { 1, 2, 3 };

        TrialClass1 trial1 = new TrialClass1(sampleList1);

        sampleList1[0] = -1;

        Console.WriteLine($"{sampleList1[0].ToString()}, {trial1.Trial1[0].ToString()}");

        List<int> sampleList2 = new List<int>() { 3, 4, 5 };

        TrialClass2 trial2 = new TrialClass2() { Trial2 = sampleList2 };

        sampleList2[0] = -4;

        Console.WriteLine($"{sampleList2[0].ToString()}, {trial2.Trial2[0].ToString()}");

        trial1.Trial1.Add(50);

        Console.WriteLine($"{sampleList1[3].ToString()}, {trial1.Trial1[3].ToString()}");

        // This does not work, uncomment and check

        // trial2.Trial2.Add(50); 

    }

}