package com.codegym.task.task04.task0442;
/*
Adding
*/
import java.io.*;
public class Solution {
public static void main(String[] args) throws Exception {
//write your code here
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
//int number = 0;
int total = 0;
while(true)
{
int a = Integer.parseInt(reader.readLine());
if(a == -1)
{
total += a;
System.out.println(total);
break;
}
//System.out.println(total);
}
}
}