Exercise - Find Pi to the nth digit

using System;

namespace random
{
    class Program
    {
        static void Main(string[] args)
        {
            //Define vars
            const double PI = Math.PI;
            int places = 0;
            bool isInt = false;

            Console.Write("PI: Enter number of digits to display, between 1-14: ");

            do
            {
                //Get user input
                string placesAsString = Console.ReadLine();

                try
                {
                    places = int.Parse(placesAsString);

                    if (places < 0)
                    {
                        places = 0;
                        Console.WriteLine("Cannot use a negative value. Decimal places set to 0.");
                        Console.WriteLine("PI at {0} decimal places: {1}", places, Math.Round(PI, places));
                        isInt = true;
                    }
                    else if (places > 14)
                    {
                        places = 14;
                        Console.WriteLine("Cannot use a value over 14. Decimal places set to 14.");
                        Console.WriteLine("PI at {0} decimal places: {1}", places, Math.Round(PI, places));
                        isInt = true;
                    }
                    else
                        Console.WriteLine("PI at {0} decimal places: {1}", places, Math.Round(PI, places));
                        isInt = true;
                }
                catch
                {
                    Console.WriteLine("Please enter a valid number");
                }
            } while (!isInt);
            Console.ReadLine();
        }

    }
}