public class Main{
  public static void main(String[] args){
    int n = new java.util.Scanner(System.in).nextInt();

    for (int i=0; ;i++){
      int tmp = (i+1)*1000 - n;
      if (tmp >= 0){
        System.out.println(tmp);
        break;
      }
    }
  }
}

/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