import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Integer price = sc.nextInt();
        Integer change = 0;

        if (price % 1000 == 0){
          Integer count_bill = (price / 1000);
          change = ((count_bill * 1000) - price); 
        }
        else{
          Integer count_bill = (price / 1000) + 1;
          change = ((count_bill * 1000) - price); 
        }
        
        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