import java.io.*;
import java.util.*;
import java.awt.Point;
public class Main {
	static Scanner sc;
	static PrintWriter out;
	static final int uncal = -1;
	static final int mod = (int) (1e9)+7;
	public static void main(String[] args) throws Exception{
		// TODO Auto-generated method stub
		sc = new Scanner(System.in); 
		out = new PrintWriter(System.out);
		int n = sc.nextInt()%1000;
		if(n > 0)
			n = 1000-n;
		out.println(n);
		out.close();
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz