import java.io.PrintWriter;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.next());
        PrintWriter out = new PrintWriter(System.out);
        if (N < 1000) {
            out.println(1000 - N);
            sc.close();
            out.flush();
            return;
        }

        int x = 0;
        x = (int) Math.ceil((double) N / 1000);

        out.println(1000 * x - N);
        sc.close();
        out.flush();
    }
}
/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