Problema POO de 6.5

#include<iostream>
#include<stdio.h>
#include <string>
#include<list>
#include <iterator>
#include <fstream>
using namespace std;

class Articol {
private:
    int tip;
    string denumire;
    double pret, cantitate;
public:
    Articol(int tip, string denumire, double pret, double cantitate) {
        this->tip = tip;
        this->denumire = denumire;
        this->pret = pret;
        this->cantitate = cantitate;
    }
    virtual void Afis() {
        cout << denumire<<" "<< pret <<" "<<cantitate<<" " ;
    }
};

class Perisabil: public Articol{
private:
    string dataExp, categ;
public:
    Perisabil(int tip, string denumire, double pret, double cantitate, string dataExp, string categ) : Articol(0, denumire, pret, cantitate) {
        this->dataExp = dataExp;
        this->categ = categ;
    }
    void Afis() {
        Articol::Afis();
        cout << dataExp << " " << categ<<endl;
    }
};

class NePerisabil : public Articol {
private:
    string domeniu, material;
public:
    NePerisabil(int tip, string denumire, double pret, double cantitate, string domeniu, string material) : Articol(1, denumire, pret, cantitate) {
        this->domeniu= domeniu;
        this->material = material;
    }
    void Afis() {
        Articol::Afis();
        cout << domeniu << " " << material << endl;
    }
};

istream &operator>>(istream &in, Articol *& a) {
    int tip;
    string denumire;
    double pret, cantitate;

    string dataExp, categ;
    string domeniu, material;

    cout << "Denumire: "; in >> denumire;
    cout << "Pret: "; in >> pret;
    cout << "Cantitate: "; in >> cantitate;
    cout << "Tip(0-Perisabil, 1-Neperisabil) "; in >> tip;

    if (tip == 0) {
        cout << "Data expirari: "; in >> dataExp;
        cout << "Categorie: "; in >> categ;
        a = new Perisabil(0, denumire, pret, cantitate, dataExp, categ);
    }
    else
    {
        cout << "Domeniu: "; in >> domeniu;
        cout << "Material: "; in >> material;
        a = new NePerisabil(1, denumire, pret, cantitate, domeniu, material);
    }
    return in;
}

ifstream &operator>>(ifstream &in, Articol *& a) {
    int tip;
    string denumire;
    double pret, cantitate;

    string dataExp, categ;
    string domeniu, material;

     in >> denumire;
     in >> pret;
     in >> cantitate;
     in >> tip;

    if (tip == 0) {
     in >> dataExp;
     in >> categ;
        a = new Perisabil(0, denumire, pret, cantitate, dataExp, categ);
    }
    else
    {
        in >> domeniu;
        in >> material;
        a = new NePerisabil(1, denumire, pret, cantitate, domeniu, material);
    }
    return in;
}

int main() {
    list<Articol *> lista;
    list<Articol *>::iterator it;
    int opt;
    Articol *a = NULL;
    ifstream f("in.txt");
    do {
        cout << "0. Iesire\n";
        cout << "1. Citire Tast\n";
        cout << "2. Afisare\n";
        cout << "3. Citire Fiser\n";
        cout << "Optiunea aleasa: "; cin >> opt;
        switch (opt)
        {
        case 0: exit(0);
        case 1:
            cin >> a;
            lista.push_back(a);
            break;
        case 2:
            for (it = lista.begin(); it != lista.end(); it++)(*it)->Afis();
            break;
        case 3:
            while (!f.eof())
            {
                f >> a;
                lista.push_back(a);
            }
            lista.erase(--lista.end() ); // stergem ulitmul elment din lista deoarece este vid
            break;
        default:
            break;
        }

    } while (1);
    return 0;
}