import java.util.*;

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

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