Why my private variables are not acessible to member functiom

void dooperation()
   {
       cout<<x+y;

   }

#include <iostream>

using namespace std;
template<class T>
class calculator
{
    protected:
    T x;
    T y;
    public:
        calculator(T m,T n)
        {
            x=m;
            y=n;

        }
    virtual void dooperation()=0;
    

};

template<class T>
class addition: public calculator<T>
{
public:
    addition(T m,T n):calculator<T>(m,n)
    {

    }
    void dooperation()
    {
        cout<<x+y;
       
    }



};

int main()
{
    addition<int> add(3,4);
    calculator <int>* ptr;
    ptr=&add;
    ptr->dooperation();
}