Can anyone explain why this try and catch method isn't working?

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            // Get number of Yays to print
            Console.Write("Enter the number of times to print \"Yay!\": ");

            var entry = Console.ReadLine();

            // Recognise number of Yays as an integer
            var numberYay = int.Parse(entry);

            try
            {
                // Print number of Yays
                while(numberYay > 0)
                {
                    Console.Write("Yay!");
                    numberYay -= 1;
                }
            }
            catch(System.FormatException)
            {
                Console.WriteLine("That is not valid input.");
            }

        }
    }
}