import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	} main {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc System.out.println(((N+999)/1000)*1000-N) System.out.println System.out System System.out ((N+999)/1000)*1000-N ((N+999)/1000)*1000 ((N+999)/1000) (N+999) N 999 1000 1000 N String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		System.out.println(((N+999)/1000)*1000-N);
	}
}