import java.util.*;
public class Main {
	public static void main(String[] args){
	    Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		sc.close();
      
      	int maisu = 0;
      	int otsuri = 0;
      	if(n%1000==0) {
          System.out.println(0);
        } else {
          maisu = n / 1000 + 1;
          otsuri = maisu * 1000 - n;
          System.out.println(otsuri);
        }
    }
}
/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