Class Problem HackerRank in C++

classHackerRank.cpp

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

class Student{
    private:
    int age, standard;
    string first_name, last_name;
    
    public:
    
    // Setter
    
      void set_age(int age) { this->age = age; }
      void set_standard(int standard) { this->standard = standard; }
      void set_first_name(string first_name) { this->first_name = first_name; }
      void set_last_name(string last_name) { this->last_name = last_name; }
    
    //  Getter
    
      int get_age() { return this->age; }
      int get_standard() { return this->standard; }
      string get_first_name() { return this-> first_name; }
      string get_last_name() { return this->last_name; }
      
    //  String Operation
      string to_string(){
          stringstream ss;
          ss << age << "," << first_name << "," << last_name << "," << standard;
          return ss.str();
      }
};

int main() {
    int age, standard;
    string first_name, last_name;

    cin >> age >> first_name >> last_name >> standard;

    Student st;
    st.set_age(age);
    st.set_standard(standard);
    st.set_first_name(first_name);
    st.set_last_name(last_name);

    cout << st.get_age() << "\n";
    cout << st.get_last_name() << ", " << st.get_first_name() << "\n";
    cout << st.get_standard() << "\n";
    cout << "\n";
    cout << st.to_string();

    return 0;
}