import java.util.*;
public class Main {

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

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

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

} Main public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	} main {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int temp = n / 1000 * 1000; temp n / 1000 * 1000 n / 1000 n 1000 1000 int result = temp == n ? 0 : temp + 1000 - n; result temp == n ? 0 : temp + 1000 - n temp == n temp n 0 temp + 1000 - n temp + 1000 temp 1000 n System.out.println(result) System.out.println System.out System System.out result String[] args args public class Main {

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

} public class Main {

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

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

	public static void main(String[] args) {
		        Scanner sc = new Scanner(System.in);
		        
		        int n = sc.nextInt();
		        int temp = n / 1000 * 1000;
		        int result = temp == n ? 0 : temp + 1000 - n;
		        System.out.println(result);

	}

}
