import java.util.Scanner;

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

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

		}
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		if (A % 1000 == 0) {
			System.out.println(0);
		} else {
			System.out.println(1000 - (A % 1000));

		}
	} main {
		Scanner sc = new Scanner(System.in);
		int A = sc.nextInt();
		if (A % 1000 == 0) {
			System.out.println(0);
		} else {
			System.out.println(1000 - (A % 1000));

		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc if (A % 1000 == 0) {
			System.out.println(0);
		} else {
			System.out.println(1000 - (A % 1000));

		} A % 1000 == 0 A % 1000 A 1000 0 {
			System.out.println(0);
		} System.out.println(0) System.out.println System.out System System.out 0 {
			System.out.println(1000 - (A % 1000));

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

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

		}
	}
} Main
import java.util.Scanner;

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

		}
	}
}