//package hiougyf;
import java.util.*;

public class Main {

	public static void main(String[] args) {
		 Scanner sc =new Scanner(System.in);
	int t=sc.nextInt();
	 int a=t%1000;
	 if(a!=0)System.out.println(1000-a);
	 else System.out.println("0");		
	}
	
}
	
/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