What will be the output of the program?

 class s1 extends Thread
 {   
    public void run()     
    {         
       for(int i = 0; i 3; i++)        
       {
            System.out.println("A");                  
            system.out.println("B");          
       }    
    }  
} 
 class Test120 extends Thread  
{    
  public void run() 
  {     
     for(int i = 0; i 3; i++)   
     {              
            System.out.println("C");              
            System.out.println("D");             
      }    
   }   
   public static void main(String args[])                 
      {       
      s1 t1 = new s1();   
      Test120 t2 = new Test120();          
      t1.start();     
      t2.start();     
   }  
}