HackerRank C++ Overloading Ostream Operator

The task is to overload the << operator for Person class in such a way that for p being an instance of class Person the result of:

std::cout << p << " " << << std::endl;

#include <iostream>

using namespace std;

class Person {
public:
    Person(const string& first_name, const string& last_name) : first_name_(first_name), last_name_(last_name) {}
    const string& get_first_name() const {
      return first_name_;
    }
    const string& get_last_name() const {
      return last_name_;
    }
private:
    string first_name_;
    string last_name_;
};
ostream& operator<<(ostream& os, const Person& pr)  
{  
    os <<"first_name=" <> first_name >> last_name >> event;
    auto p = Person(first_name, last_name);
    cout << p << " " << event << endl;
    return 0;
}