import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner stdIn = new Scanner(System.in);
    int a = stdIn.nextInt();
   
    if(a % 1000 == 0)
    System.out.print(0);
    
    else if(a % 1000 != 0)
      System.out.print(1000 - a % 1000);
  }
}
/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