package com.javarush.task.task04.task0442;
import java.io.*;
/*
Суммирование
*/

public class Solution {
    static public int sum;
    public static void main(String[] args) throws Exception {
         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));


        while(true)
       {
        int number = Integer.parseInt(reader.readLine());
        sum = sum + number;

           if(number == -1)
           {
               System.out.print(sum);
               break;
           }
       }

    }
}