import java.util.*;

public class Main {
	public static void main(String[] args){
	Scanner scn = new Scanner(System.in);
      int p = scn.nextInt();
      int a = p%1000;
      int ans = 1000-a;
      if(a==0){
        System.out.println("0");
      }else{
      	System.out.println(ans);
      }
	}
}

/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