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


class Main {

    public static void main(String[] args) throws IOException
    {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int n = Integer.parseInt(br.readLine());
        int answer = (int)(Math.ceil(n/1000.0));
        out.println(answer*1000 - n);

        out.flush();
        out.close();

    }

    static class pair{
        long x1;
        long x2;

        public pair(long x1 , long x2)
        {
            this.x1 = x1;
            this.x2 = x2;
        }

    }

}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz