import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int N=scanner.nextInt();
		int change= (1000-(N%1000));
		if (N%1000==0) {
			System.out.println("0");
		}else {
			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