/**
 * GradeAverager.java
 *
 * Computer Science S-111
 * 
 * Demonstrates the use of: 
 *    - the cumulative-sum loop pattern
 *    - an if-else statement to handle invalid user inputs 
 */

import java.util.*;

public class GradeAverager {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);

        System.out.print("number of grades? ");
        int numGrades = console.nextInt();
        
        if (numGrades <= 0) {
            System.out.println("nothing to average");
        } else {
            // An example of the cumulative-sum loop pattern.
            int sum = 0;
            for (int i = 1; i <= numGrades; i++) {
                System.out.print("grade #" + i + ": ");
                int grade = console.nextInt();
                sum = sum + grade;
            }
         
            System.out.println("The average is " +
              (double)sum / numGrades);
        }
    }
}