class Base { int ping() { return 1; } }

class Repo {
  int load(int key) { return key; }
  int save(int row) { return row; }
}

class Service extends Base {
  Repo repo;
  Service(Repo repo) { this.repo = repo; }
  int run(int key) {
    int row = this.repo.load(key);
    return this.repo.save(row);
  }
}
