import java.util.Scanner;

/** Demo the use of assert.  Also, Java's modulus/remainder operator.
    @author Jed Yang, 2017-04-05

    Try some negative inputs, get confused, then run this with
      java -ea AssertDemo
    and try those negative inputs again.

    https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html#usage-invariants
*/
public class AssertDemo
{
   public static void main(String[] args)
   {
      System.out.print("Positive integer, please: ");
      Scanner kb = new Scanner(System.in);
      int number = kb.nextInt();

      if (number % 3 == 0)
      {
         System.out.println("Multiple of three.");
      }
      else if (number % 3 == 1)
      {
         System.out.println("Multiple of three, plus 1.");
      }
      else
      {
         assert number % 3 == 2 : number % 3;
         System.out.println("Multiple of three, plus 2.");
      }
   }
}