import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		//test
		Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());

		System.out.println(((N % 1000) == 0) ? 0 : 1000 - (N % 1000));
	}

}

/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