import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args) {
		int price;
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

		try {
			price =Integer.parseInt(reader.readLine());
			System.out.println((10000 - price) % 1000);
		} catch (IOException e) {
			// TODO 自動生成された catch ブロック
			e.printStackTrace();
		}

	}
}

/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