Как сделать сортировку по ФИО [дубликат]

using namespace std;
class Student {
public:
        string F;
        string I;
        string:O;
public:
        Student(string const & firstname, string const & middlename, string  const & lastname)
                 : F(lastname)
                 , I(firstname)
                 , O(middlename)
       {}
};
ostream & operator << (ostream & out, Student const & stud)
{
         out << stud.I << '  '  <<stud.O <<  '  '  <<stud.F;
         return out;
}
int main() {
         Student a = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         Student b = Student ("Maxim", "Viktorovich", "Kim");
         Student c = Student ("Artem", "Vyacheslavovich", "Bargadaev");
         Student d = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         Student v = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         Student e = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         Student h = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         Student k = Student ("Denis", "Vyacheslavovich", "Stepanenko");
         strin buffer;
         vector<Student>Students;
         for (int i=0; i < 10; i++) {
         Students.push_back(a);
         Students.push_back(b);
         Students.push_back(c);
         }
         for (i = 0;i < 10; i++) {
                std:vector<std::string>;
                // Тут должна быть сортировка
                std::cout << Students[i] << std::endl;
        }
        _getch();
        return 0;
}