import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		sc.close();
		
		int res = 0;
		if(n % 1000 == 0)
			res = 0;
		else
			res = Math.abs(n % 1000 - 1000);
		System.out.println(res);
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		sc.close();
		
		int res = 0;
		if(n % 1000 == 0)
			res = 0;
		else
			res = Math.abs(n % 1000 - 1000);
		System.out.println(res);
	}

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

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		sc.close();
		
		int res = 0;
		if(n % 1000 == 0)
			res = 0;
		else
			res = Math.abs(n % 1000 - 1000);
		System.out.println(res);
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		sc.close();
		
		int res = 0;
		if(n % 1000 == 0)
			res = 0;
		else
			res = Math.abs(n % 1000 - 1000);
		System.out.println(res);
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		sc.close();
		
		int res = 0;
		if(n % 1000 == 0)
			res = 0;
		else
			res = Math.abs(n % 1000 - 1000);
		System.out.println(res);
	}

}