import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int n, res;
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        if (n % 1000 != 0) {
            res = 1000 - n % 1000;
            System.out.println(res);

        } else System.out.println("0");

    }
}

/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