import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    System.out.println(999 - (n-1)%1000);
    sc.close();
  }
} import java.util.*; util.* java class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    System.out.println(999 - (n-1)%1000);
    sc.close();
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    System.out.println(999 - (n-1)%1000);
    sc.close();
  } main {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    System.out.println(999 - (n-1)%1000);
    sc.close();
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc System.out.println(999 - (n-1)%1000) System.out.println System.out System System.out 999 - (n-1)%1000 999 (n-1)%1000 (n-1) n 1 1000 sc.close() sc.close sc String[] args args
import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    System.out.println(999 - (n-1)%1000);
    sc.close();
  }
}