Why can't I pass this object?

using System;


namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            int count;
            while (true)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                try
                {
                    count = int.Parse(Console.ReadLine());
                    break;
                }
                catch (FormatException)
                {
                    Console.WriteLine("You must enter a whole number.");
                }
                catch (ArgumentNullException)
                 {
                    Console.WriteLine("You must enter a whole number.");
                }
            }

            for (int i = 0; i < count; i++)
            {
                Console.Write("Yay!");
            }

        }
    }
}