import java.util.*;
import java.lang.*;
import java.io.*;
public class Main {

	public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	}

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

	public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	}

} Main public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	} main {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int n =Integer.parseInt(br.readLine()); n Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br System.out.println(n%1000==0?0:1000-n%1000) System.out.println System.out System System.out n%1000==0?0:1000-n%1000 n%1000==0 n%1000 n 1000 0 0 1000-n%1000 1000 n%1000 n 1000 String[] args args public class Main {

	public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	}

} public class Main {

	public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	}

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

	public static void main(String[] args)throws java.lang.Exception
    {		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n =Integer.parseInt(br.readLine());
		System.out.println(n%1000==0?0:1000-n%1000);
	}

}
