import java.util.*;
import java.io.*;
public class Main{
 public static void main(String agrs[])
 {
   Scanner in = new Scanner(System.in);
   PrintWriter out = new PrintWriter(System.out);
   int n = in.nextInt();
   if(n % 1000 == 0)
   {
     out.println(0);
   }
   else
   {
     out.println((n / 1000 + 1) * 1000 - 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