import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int calc = N % 1000;
        int readyMoney = 0;
        if (calc == 0) {
            readyMoney = 1000 * (N / 1000);
        } else {
            readyMoney = 1000 * (N / 1000 + 1);
        }
        int change = readyMoney - N;
        System.out.println(change);
    }
}
/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