using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        object arr = new int[1];

        var fastCast = (IReadOnlyCollection<int>)arr;

        var slowCast = arr as IReadOnlyCollection<int>;

        Console.WriteLine($"Array as fast cast {(fastCast == default ? "is null" : "is valid")}");

        Console.WriteLine($"Array as slow cast {(slowCast == default ? "is null" : "is valid")}");

    }

}