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