using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World="+Truncate(10.0101010101, 4));

    }

    public static double Truncate(double value, int precision)

    {

      return Math.Truncate(value * Math.Pow(10, precision)) / Math.Pow(10, precision);

    }

}