import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
    	int n;
    	int senCount=0;
    	Scanner sc=new Scanner(System.in);
    	n=sc.nextInt();
	
    	if((n%1000)!=0){
        	int amari=1000-(n%1000);
        	System.out.println(amari);
    	}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