package com.codegym.task.task04.task0442;


/*
Adding

*/

import java.io.*;
import java.util.Scanner;

public class Solution {
    public static void main(String[] args) throws Exception {
        //write your code here
        int a = 0;
        int sum = 0;
        Scanner scan = new Scanner(System.in);
        while(true){
            a = scan.nextInt();
            if(a==-1){
                sum--;
                System.out.println(sum);
                break;
            }
            sum +=a;
        }
    }
}