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((N / 1000 + 1)*1000 - N);
      }
    }
}
       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((N / 1000 + 1)*1000 - N);
      }
    }
} 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((N / 1000 + 1)*1000 - N);
      }
    } main {
		Scanner sc = new Scanner(System.in);
      int N = sc.nextInt();
      if(N % 1000 == 0){
        System.out.println(0);
      }else{
        System.out.println((N / 1000 + 1)*1000 - N);
      }
    } 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((N / 1000 + 1)*1000 - N);
      } 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((N / 1000 + 1)*1000 - N);
      } System.out.println((N / 1000 + 1)*1000 - N) System.out.println System.out System System.out (N / 1000 + 1)*1000 - N (N / 1000 + 1)*1000 (N / 1000 + 1) N / 1000 N 1000 1 1000 N 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((N / 1000 + 1)*1000 - N);
      }
    }
} 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((N / 1000 + 1)*1000 - N);
      }
    }
} 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((N / 1000 + 1)*1000 - N);
      }
    }
}
      