#include <iostream>
#include <map>
#include <vector>

class priority_queue {
    std::map<int, std::vector<std::string> > queue;
public:
    void add(std::string str,int priority) {
        if(!queue[priority].empty()) {
            queue[priority].push_back(str);
        } else {
            std::vector<std::string> vec;
            vec.push_back(str);
            queue[priority] = vec;
        }
    }
    std::string remove() {
        if(!queue.begin()->second.empty()) {
            std::string temp = queue.begin()->second[0];
            queue.begin()->second.erase(queue.begin()->second.begin());
            if(queue.begin()->second.empty())
                queue.erase(queue.begin());
            return temp + "\n";
        }
        std::cout << "ERROR: QUEUE EMPTY!" << std::endl;
        return "";
    }
};


int main() {
    priority_queue q;

    q.add("X",10);
    q.add("Y",1);
    q.add("Z",3);

    std::cout << q.remove();
    std::cout << q.remove();
    std::cout << q.remove();
}