import java.util.Scanner;

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