using System;  

using System.Threading;  

class Printer{ 

    static readonly object obj = new object();

    public void PrintTable(){ 

        lock (obj){  

            for (int i = 1; i <= 5; i++){

                Console.WriteLine("i = {0}", i);

            }  

        }  

    }  

}  

public class Program{  

    public static void Main(string[] args){  

        Printer p = new Printer();  

        Thread t1 = new Thread(new ThreadStart(p.PrintTable));  

        ThreadStart begin = new ThreadStart(p.PrintTable);

        Thread t2 = new Thread(begin);

        t1.Start();  

        t2.Start();

    }  

}