/*
 * REPETITION (sentinel-controlled while loop): keep reading until the
 * special value -1 (the sentinel) is entered. Then a SELECTION guards
 * against dividing by zero.
 *
 * Flowchart:
 *   (Start)
 *     -> [sum = 0, count = 0]
 *     -> /Input num/
 *     -> <num != -1?> <---------------------------+
 *          True  -> [sum = sum + num, count++]    |
 *                -> /Input num/ ------------------+
 *          False -> <count > 0?>
 *                     True  -> /Print sum / count/ --+
 *                     False -> /Print "No numbers"/ -+-> (End)
 */
import java.util.Scanner;

public class SentinelAverage {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int sum = 0;
        int count = 0;

        System.out.print("Enter a number (-1 to stop): ");
        int num = sc.nextInt();

        while (num != -1) {
            sum = sum + num;
            count++;
            System.out.print("Enter a number (-1 to stop): ");
            num = sc.nextInt();
        }

        if (count > 0) {
            System.out.println("Average = " + (double) sum / count);
        } else {
            System.out.println("No numbers entered.");
        }
        sc.close();
    }
}