import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc=  new Scanner(System.in);

        int num = sc.nextInt();

        float f = num/1000f;

        int l = (int)(Math.ceil(f));
        System.out.println(l*1000-num);
    }
}

/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