1

import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {

    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

    int sum = 0;

    while (true) {
        String num1 = reader.readLine();
        int num = Integer.parseInt(num1);
        sum = sum + num;

        if (num == -1) {
            System.out.println(sum);
            break;
        }

    }
    }
}