import java.util.Scanner;
public class Main
{
  public static void main(String[] args)
  {
    Scanner sc = new Scanner(System.in); 
    int a  = sc.nextInt();
    int r = a % 1000;
    int s = 1000 - r;
    if(s == 1000)
    {
    System.out.println("0");
    }
    else
    {
    System.out.println(s);
    }
  }
}                          

/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