import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
	Scanner scan = new Scanner(System.in);
	int N = scan.nextInt();
	scan.close();
	int remainder;
	if((N % 1000) == 0) {
		remainder = 0;
	}
	else {
		remainder = 1000 - N % 1000;
	}
	System.out.println(remainder);
	}
	}
/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