import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int price = sc.nextInt();
        
        if(1000 >= price) {
            System.out.println(1000 - price);
        } else {
            int surplus = price % 1000;
            int change  = 0;
            if(0 != surplus) {
                change = 1000 - surplus;
            }
            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