Multi-level inheritance in OOP

* /program to illutrate multilevel inheritance./ *
#include < iostream > using namespace std;
class student
{
    protected: int roll;
    public: void getdata(int);
    void putdata(void);
};
void student::getdata(int a)
{
    roll = a;
}
void student::putdata()
{
    cout << "\nrollno:" << roll;
}
class test: public student
{
    protected: float sub1;
    float sub2;
    public: void get(float, float);
    void put(void);
};
void test::get(float x, float y)
{
    sub1 = x;
    sub2 = y;
}
void test::put()
{
    cout << "\n'c' marks:" << sub1;
    cout << "\n'c++' marks:" << sub2;
}
class result: public test
{
    float total;
    public: void display(void);
};
void result::display(void)
{
    total = sub1 + sub2;
    putdata();
    put();
    cout << "\ntotal=" << total;
}
int main()
{
    result stu;
    stu.getdata(150);
    stu.get(78.0, 65.8);
    stu.display();
    return 0;
}