using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[] factorsOf300 = {2, 2, 3, 5, 5};

​

        var uniqueFactors = factorsOf300.Distinct().Count();

​

        Console.WriteLine("There are {0} unique factors of 300.", uniqueFactors);   

    }

}