import java.util.Scanner;

class Main{
  public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int n = sc.nextInt();
   int money;
   if(n%1000 == 0){
    money = n;
   }else{
    money = ((n/1000)+1)*1000;
   }
   System.out.println(money-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