import java.util.*;
import java.io.*;
import java.lang.*;
 
public class Main {
 	public static void main (String[] args) {
     	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	while (n>=1000) {
         	n-=1000; 
        }
      	System.out.println(n==0 ? n : 1000-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