int main() {
    std::vector<int> a;
    std::vector<int> b;

    /*
        - switch X, X = {1,2}
        - add Y
        - show
        - pop
    */
    std::string s;
    vector<int>* current = &a;
    while (std::cin >> s) {
        if (s == "switch") {
            int num;
            std::cin >> num;
            if (num == 1) {
                current = &a;
            } else {
                current = &b;
            }
        } else if (s == "add") {
            int y;
            std::cin >> y;
            current->push_back(y);
        } else if (s == "show") {
            for (auto elem : *current) {
                std::cout << elem << " ";
        } else {
            current->pop_back(); // хайп.
        }
    }


}