public class Numbers
{
   /**
      Computes a sum of even integers
      @param a the lower bound (may be odd or even)
      @param b the upper bound (may be odd or even)
      @return the sum of even integers between a and b (inclusive).
   */
   public int evenSum(int a, int b)
   {
      if(a > b){return 0;}
      return (a % 2 == 0) ? a + evenSum(++a, b) : evenSum(++a, b);
   }
}