import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int price = scan.nextInt(); // 商品価格
        scan.close();
        int num1000 = price / 1000; // 必要な1000円の枚数-1
        if (price % 1000 == 0) {
            // 価格が1000円で割り切れるときはお釣り０
            System.out.println("0");
        } else {
            System.out.println(1000 * (num1000 + 1) - price);
        }
    }
}
/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