using System;

using System.Collections.Generic;

​

public class Program

{

    static IList<int> SelectedCps { get; set;}

    static bool is1or2() => SelectedCps.Count is 1 or 2;

    static bool isInInterval1_2() => SelectedCps.Count is >=1 and <=2;

    public static void Main()

    {

        var list = new List<int>();

        for(int i = 0; i < 100; i++){

            test(list);

            list.Add(i);

        }

        System.Console.WriteLine("Test succeeeded");

    }

    public static void test(List<int> l)

    {

        SelectedCps = l;

        if(isInInterval1_2() != is1or2())

            throw new Exception($"count = {SelectedCps.Count}");        

    }

}