05. Parking Lot

#include <iostream>
#include <string>
#include <set>

using namespace std;

int main() {
    string line, command, numberPlate;
    getline(cin, line);

    set<string> numberPlates;

    while (line != "END") {
        command = line.substr(0, line.find(','));
        numberPlate = line.substr(line.find(',') + 2);

        numberPlates.insert(numberPlate);

        if (command == "OUT") {
            numberPlates.erase(numberPlate);
        }

        getline(cin, line);
    }

    if (numberPlates.empty()) {
        cout << "Parking Lot is Empty\n";
    }
    for (auto& n : numberPlates) {
        cout << n << endl;
    }

    return 0;
}