using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        double amount = 39.00;

        string decimalPoint = (amount).ToString();

        decimalPoint = decimalPoint.Substring(decimalPoint.IndexOf(".") + 1);

        if( decimalPoint.Length > 0)

            Console.WriteLine(string.Format(new CultureInfo("en-US"),"{0:C" + decimalPoint.Length +"}", amount));

        else

            Console.WriteLine(string.Format(new CultureInfo("en-US"),"{0:C0}", amount));

​

    }

}