import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

} Main public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	} main {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = Integer.parseInt(sc.nextLine()); N Integer.parseInt(sc.nextLine()) Integer.parseInt Integer sc.nextLine() sc.nextLine sc System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000)) System.out.println System.out System System.out ((N % 1000) == 0) ? 0 : 1000 - (N % 1000) ((N % 1000) == 0) (N % 1000) N 1000 0 0 1000 - (N % 1000) 1000 (N % 1000) N 1000 String[] args args public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

} public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

}
