import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	}
} 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(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	} main {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		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 check = n % 1000; check n % 1000 n 1000 int result = 0; result 0 if (check != 0) {
			result = 1000 - check;
		} check != 0 check 0 {
			result = 1000 - check;
		} result = 1000 - check result 1000 - check 1000 check 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(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	}
} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt(); // 文字列
		
		int check = n % 1000;
		int result = 0;
		
		if (check != 0) {
			result = 1000 - check;
		}

		System.out.println(result);
	}
}