import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int n = scan.nextInt(); n scan.nextInt() scan.nextInt scan 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 scan.close() scan.close scan String[] args args public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    }
} public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        System.out.println(n % 1000 == 0 ? 0 : 1000 - (n % 1000));
        scan.close();
    }
} Main
import java.util.*;

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