class Subjects
{
   void Welcome()
   {
       System.out.print("Hello ");	
   }
   
   int Mark()
   {
   	   int m;
   	   m = (int)(Math.random() * 9);
   	   return m;
   }
}	
	
class Computer_Science extends Subjects
{
   void Welcome()
   {
   	   System.out.println("computer science teacher!");
   }
   
   int Mark()
   {
   		m= ++m;/*It's computer science after all, not LITHUANIAN*/ 
   }
   	
}

class Lithuanian extends Subjects
{
   void Welcome()
   {
      System.out.println("Lithuanian teacher.");	
   	
   }	

   int Mark()
   {
      m= --m;
      return m;
   }	
	
}