#include <iostream>
#include <set>
using namespace std;

class Student
{
    unsigned id;
    string name;
public:
    Student() = delete;
    Student(unsigned arg1, string arg2 = "") : id(arg1), name(arg2) {}
    Student(const Student&) = default;
    bool operator<(const Student& obj) const
    {
        return id < obj.id;
    }
    bool operator==(const Student& obj) const
    {
        return id == obj.id;
    }
    friend ostream& operator<<(ostream& out, const Student& obj)
    {
        out << obj.id << "   " << obj.name;
        return out;
    }
};

ostream& operator<<(ostream& out, const set<Student>& stu)
{
    for (auto it = stu.cbegin(); it != stu.cend(); ++it)
    {
        out << *it << endl;
    }
    return out;
}

int main()
{
    set<Student> Students;
    Students.insert({117,"John"});
    Students.insert({124,"Paul"});
    Students.insert({102,"George"});
    Students.insert({106,"Ringo"});
    Students.insert({223,"Peter"});
    Students.insert({203,"Paul"});
    Students.insert({243,"Mary"});

    cout << "Students.size() = "  << Students.size() << endl;
    cout << Students << endl;

    bool insertSuccess;
    cout << boolalpha;

    insertSuccess = Students.insert({309,"Mick"}).second;
    cout << "insert 309: " << insertSuccess << endl;
    insertSuccess = Students.insert({117,"Nobody"}).second;
    cout << "insert 117: " << insertSuccess << endl << endl;

    cout << "find 106: " << *(Students.find(106)) << endl;  // How does this work?
    //  cout << *(Students.find(107)) << endl;  // ERROR

    unsigned id;
    set<Student>::const_iterator it;
    cout << "find 203: " << (Students.find(203) != Students.end()) << endl;
    cout << "find 107: " << (Students.find(107) != Students.end()) << endl << endl;

    cout << "Before erase: Students.size() = "  << Students.size() << endl;
    id = 203;
    Students.erase(Students.find(id));  // Did this work?
    cout << "After erase of 203: Students.size() = "  << Students.size() << endl;
    cout << "Students.erase(102) = " << Students.erase(102) << endl;
    cout << "Students.erase(103) = " << Students.erase(103) << endl;
}