import java.util.Scanner;

public class Main {
    public static void abc173_a() {
        try (Scanner sc = new Scanner(System.in)) {
            int a = Integer.parseInt(sc.next());
            int change = a % 1000;
            if (change == 0)
                System.out.println(0);
            else
                System.out.println(1000 - change);
        }
    }


    public static void main(String[] args) {
        abc173_a();
    }
}
/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