import java.util.*;
import java.lang.*;
import java.io.*;
class Main {
    public static void main(String args[]) {
      Scanner sc = new Scanner(System.in);
      int N = sc.nextInt();
      int bill = 1000;
        while(N>bill)
        {
            bill = bill + 1000; 
        }
        System.out.println(bill-N);
    }
}
/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