public class Add
   {
       private int z;
       
       public Add (int x, int y) throws IntegerOverflowException
       {
           IntegerOverflowException ex = new IntegerOverflowException ("Integer overflow");
           z = x + y;
           if (x>0 && y>0 && z<0)  throw ex;
       }
       public double getValue ()
       {
           return z;
       }
   }