import java.util.Scanner;

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

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