import java.util.Scanner;

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

