import java.util.*;

public class Main
{
	public static void main(String[] args)
	{
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	}
} import java.util.*; util.* java public class Main
{
	public static void main(String[] args)
	{
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	}
} Main public static void main(String[] args)
	{
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	} main {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int n=sc.nextInt(); n sc.nextInt() sc.nextInt sc n=(n%1000==0)? 0:1000-(n%1000) n (n%1000==0)? 0:1000-(n%1000) (n%1000==0) n%1000 n 1000 0 0 1000-(n%1000) 1000 (n%1000) n 1000 System.out.println(n) System.out.println System.out System System.out n 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();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	}
} public class Main
{
	public static void main(String[] args)
	{
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		n=(n%1000==0)? 0:1000-(n%1000);
		System.out.println(n);
		sc.close();
	}
} Main
import java.util.*;

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