
import java.util.*;
import java.io.*;

public class Main {

  public static void main(String[] args) {

      Scanner in = new Scanner(System.in);
      int N = in.nextInt();
      int bill = 1000;

      if(N%bill==0)
      {


          System.out.println(0);
      }
        else
      {
          int no_of_notes = N/bill + 1;
          System.out.println(no_of_notes*1000-N);
      }
  }

}

/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