import java.util.Scanner;

public class Main{
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int total = scan.nextInt();
    int noguti = 0;
    if(total < 1000){
     System.out.print(1000- total);
    }
    if(total > 999 && total % 1000 == 0){
     System.out.print(0);
    }
    if(total > 999 && total % 1000 != 0){
     noguti = (total/1000)+ 1;
    System.out.print(1000*noguti - total);
    }    
  }
}
/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