import java.util.Scanner;

class Main{
    static public void main(String[] args){
      Scanner sc = new Scanner(System.in);

      int n;
      n = sc.nextInt();

      int x = (n+1000-1)/1000;
      int change = x*1000 - n;

      System.out.println(change);
      }
}

/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