import java.util.*;
 
class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    if (N%1000 == 0){
      System.out.println(0);
    }else if (N<=1000&&0<N){
      System.out.println(1000-N);
    }else if(1000<N&&N<10000){
      System.out.println(1000-N%1000);
    }
  }
}

/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