struct list_node {
    train* data;
    list_node* next;
}

struct train {
    string destination;
    int id;
    unsigned int arrivalTime;
}

class TrainList {
    list_node *head;

public:
    TrainList() {head = NULL;}
    ~TrainList();

    bool checkTrainIdValid(int id);
    void add();
    void remove();
    void show();

    void save();
    void load();
}

TrainList::~TrainList() {
    while (head != NULL) {
        list_node *tmp = head->next;
        delete head;
        head = tmp;
    }
}

bool TrainList::checkTrainIdValid(int id) {
    list_node *iter = head;
    while (iter != NULL) {
        if (iter->id == id) {
            cerr << "Train with such id already exists!!!" << endl;
            return false;
        }
    }

    return true;
}