import java.util.*;

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

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		System.out.print((1000-n%1000)%1000);
	}
	
}
