#include <queue>
#include <iostream>

struct Person {
    std::string name;
    int age;
};

struct CompareByAge {
    bool operator()(const Person& p1, const Person& p2) const {
        return p1.age < p2.age;
    }
};

int main() {
    std::priority_queue<Person, std::vector<Person>, CompareByAge> pq;

    pq.push({"Alice", 25});
    pq.push({"Bob", 30});
    pq.push({"Charlie", 20});

    while (!pq.empty()) {
        std::cout << pq.top().name << " ";
        pq.pop();
    }

    return 0;
}