import java.util.*;
import java.util.Scanner;
import java.lang.*;

public class Main
{
  public static void main(String args[])
  {
    try
    {
    int n,rem=0,res=0;
    Scanner s=new Scanner(System.in);
    n=s.nextInt();
    rem=n%1000;
    if(rem!=0)
    {
       res=1000-rem;
    }
    System.out.println(res);
    }
    catch(Exception e)
    {
      return ;
    }
  }
}
      
   
    
/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