C++ program to display a message by using multiple virtual function

#include<iostream>
#include<conio.h>

class students
{
    public:
        virtual first()
        {
            std::cout<<"First class marks"<<std::endl;
        }
        virtual second()
        {
            std::cout<<"Second class marks"<<std::endl;
        }
        void third()
        {
            std::cout<<"Third class marks"<<std::endl;
        }
};

class nstudents:public students
{
    public:
        first()
        {
            std::cout<<"First class marks 1"<<std::endl;
        }
        second()
        {
            std::cout<<"Second class marks 1"<<std::endl;
        }

};

class nsstudents:public students
{
    public:
        first()
        {
            std::cout<<"First class marks 2"<<std::endl;
        }
        second()
        {
            std::cout<<"Second class marks 2"<<std::endl;
        }
        third()
        {
            std::cout<<"Third class marks 2"<<std::endl;
        }
};

class nsstudents1:public students
{
    public:
        second()
        {
            std::cout<<"Second class marks 3"<<std::endl;
        }
        third()
        {
            std::cout<<"Third class marks 3"<<std::endl;
        }

};

int main()
{
    system("cls");

    students *ptr1;
    students ns;

    ptr1 = &ns;
    ptr1->first();
    ptr1->second();
    ptr1->third();

    students *ptr2, *ptr3, *ptr4;
    nstudents cloth;
    nsstudents sports;
    nsstudents1 surgical;

    ptr2->first();
    ptr2->second();
    ptr3->first();
    ptr3->second();
    ptr4->first();
    ptr4->second();
    ptr2->third();
    ptr3->third();

    getch();
    return 0;
}

First class marks
Second class marks
Third class marks
First class marks1
Second class marks1
First class marks2
Third class marks2
First class marks3
Second class marks3
Third class marks
Third class marks