import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        String[] price = String.valueOf(n).split("");

        if (n <= 1000) {
            System.out.println(1000 - n);
            return;
        }

        if (Integer.parseInt(price[1]) == 0 && Integer.parseInt(price[2]) == 0 && Integer.parseInt(price[3]) == 0) {
            System.out.println(0);
            return;
        }

        System.out.println((Integer.parseInt(price[0]) + 1) * 1000 - n);
    }
}
/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