import java.util.Scanner;

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);
		}

		sc.close();
	}

} 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();

		if (n % 1000 == 0) {
			System.out.println(0);
		} else {
			System.out.println((n / 1000 + 1) * 1000 - n);
		}

		sc.close();
	}

} 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);
		}

		sc.close();
	} 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);
		}

		sc.close();
	} 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 sc.close() sc.close sc 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);
		}

		sc.close();
	}

} 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);
		}

		sc.close();
	}

} Main
import java.util.Scanner;

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);
		}

		sc.close();
	}

}
