import java.util.Scanner;

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

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