import java.io.*;

public class Solution {
    public static void main(String[] args) throws Exception {
        for (; true; ) {
            BufferedReader x = new BufferedReader(new InputStreamReader(System.in));
            String sI = x.readLine();
            int i = Integer.parseInt(sI);
            int a = a + i;
            if (i==-1)
                System.out.println(a);
            break;

        }
    }
}