import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    }

} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    }

} Main public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    } main {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    } @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000) System.out.println System.out System System.out n % 1000 == 0 ? 0 : 1000 - n % 1000 n % 1000 == 0 n % 1000 n 1000 0 0 1000 - n % 1000 1000 n % 1000 n 1000 String[] args args public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    }

} public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - n % 1000);
    }

}
