using System;

public class Program

{

    public static void Main()

    {

        string _strFullPath = @"C:\CopyJobs\Log\CSFBGSVC_CSFinmaAlertSvc\CSFBGSVC_CSFinmaAlertSvc_PRD_Log.txt" ;

        string _strFolder = _strFullPath.Substring(0, _strFullPath.LastIndexOf("\\"));

        string _strFile = _strFullPath.Replace(_strFolder + "\\", "");

        string _strApplication = _strFile.Substring(0, _strFile.LastIndexOf("_"));

        Console.WriteLine(_strApplication);

    }

}