using System;

public class Program

{

    public static void Main()

    {

        string strInstalledVersion = "2.1.55.0";

        string strLatestVersion = "2.2.5.4";

        var vInstalledversion = new Version(0,0);

        var vstrLatestVersion = new Version(0,0);

        if (!string.IsNullOrEmpty(strInstalledVersion))

            vInstalledversion = new Version(strInstalledVersion);

        if (!string.IsNullOrEmpty(strLatestVersion))

            vstrLatestVersion = new Version(strLatestVersion);

        if (vInstalledversion.CompareTo(vstrLatestVersion)<0)

        {

            Console.WriteLine("You are using the ATLAS " + strInstalledVersion+ " version. Install the latest ATLAS Version:" + strLatestVersion);

        }

        else 

        {

            Console.WriteLine("You are using the latest ATLAS Version:" + strInstalledVersion);

        }

    }

}

​