import java.util.*;  

// This program prompts the user for numbers until -1 is entered 
// and then outputs the sum of those numbers.
public class SentinelSum {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        int number = 1;  // dummy value
        int sum = 0;
        
        System.out.print("Enter a number (-1 to quit): ");
        number = console.nextInt();
        
        while (number != -1) {
            sum += number;
            System.out.print("Enter a number (-1 to quit): ");
            number = console.nextInt();
        }
        
        System.out.println("The sum is " + sum);
    }
}