interface Calculation 
   {
            int var = 0;
            void calculate(int num);
   }
   
 class display implements Calculation 
        {
            int p;
         public  void calculate(int num)
          {
                if (num<2)
                {
                    p = var;
                }
                else
                {
                    p = num * num; 
                }
            }
        }
        
public class interfaces_Example
  {
 
            public static void main(String args[]) 
            {
                display[] array = new display[4];
 
               for(int k=0; k<4; k++)
               array[k] = new display();
               array[0].calculate(0);    
               array[1].calculate(2);
               array[2].calculate(4);
               System.out.print(array[0].p+" " + array[1].p + " " + array[2].p);
            }
   }