using System;
using System.Threading;

class Program {
  public static void DoWork(object obj) {
     Console.WriteLine("Child thread starts");

     if (obj is String)
       Console.WriteLine(obj as String);
     else
       throw new ArgumentException("Parameter is not a string.", nameof(obj));
     
     Console.WriteLine("Child thread goes to sleep");
     Thread.Sleep(5000); // the thread is paused for 5000 milliseconds
     Console.WriteLine("Child thread resumes and finishes");
  }
  
  static void Main(string[] args) {
     ParameterizedThreadStart childJob = new ParameterizedThreadStart(DoWork);
     Console.WriteLine("Main thread starts");
     
     Thread childThread = new Thread(childJob);
     childThread.Start("Message from Main");

     Console.WriteLine("Main thread waiting");
     childThread.Join();
     Console.WriteLine("Main thread finishes");
  }
}