import java.util.Scanner;

/**
 * A class to sum up numbers provided by the user.
 *
 * @author Mark Young (A00000000)
 */
public class SumNumbers {

    public static final Scanner KBD = new Scanner(System.in);

    public static void main(String[] args) {
        int num, sum;

        // introduce yourself
        System.out.println("Enter some positive integers below "
                + "and I'll tell you their sum.");

        // add up the user input
        sum = 0;
        while ((num = KBD.nextInt()) >= 0) {
            sum += num;
        }

        // report result
        System.out.println("Their sum is " + sum + ".");
    }

}