import java.util.*;
 
public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    }
} 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 answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    }
} Main public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    } main {
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int answer = 1000 - N; answer 1000 - N 1000 N while(answer < 0){
            	answer += 1000;
            } answer < 0 answer 0 {
            	answer += 1000;
            } answer += 1000 answer 1000 System.out.println(answer) System.out.println System.out System System.out answer String[] args args public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    }
} public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    }
} Main
import java.util.*;
 
public class Main{
	public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
      		int N = sc.nextInt();
      		int answer = 1000 - N;
      		while(answer < 0){
            	answer += 1000;
            }
      		System.out.println(answer);
    }
}