#include <iostream>
   
   using namespace std;
   
   // Definition for Class SL
   class SL {
   private: // Each object contains two values
       int *ptr;  // Pointer to int
       int val;   // Just an int
   public: // Member functions
       SL();
       ~SL();
       SL(const SL &);
       SL SL::operator=(const SL & fr);
       friend ostream & operator<<(ostream & os, const SL &);
       friend istream & operator>>(istream &, SL &);
       void Erase();
   };
   
   // Constructor for Class SL
   SL::SL()
   {ptr = 0;
    cout << "allocated SL " << this << endl;
   }
   
   SL::~SL()
   {cout << "deallocated SL " << this << endl;
    this->Erase();}
   
   // Copy Constructor for Class SL
   SL::SL(const SL & fr)
   {cout << "Copy Constructructor from SL " << &fr << " to SL " << this << endl;
      this->val = fr.val;
      this->ptr = 0;
      if (fr.ptr)
         {ptr = new int;
          *ptr = *(fr.ptr);
         }
      return;
   }
   
   SL SL::operator=(const SL & fr){
      cout << "Assignment Operator from SL " << &fr << " to SL " << this << endl;
      // Avoiding potential Memory Leak here.
      if (this == &fr) return (fr);
      this->val = fr.val;
      this->ptr = 0;
      if (fr.ptr)
         {ptr = new int;
          *ptr = *(fr.ptr);
         }
      return (*this);
   }
   
   ostream & operator<<(ostream & os, const SL & fr)
   {   if (fr.ptr == 0)
         {os << "data " << " 0 value none int " << fr.val << endl; return os;}
      os << "data " << fr.ptr << " value " << *(fr.ptr) << " int " << fr.val << endl;
      return os;
   }
   
   istream & operator>>(istream & is, SL & fr)
   { int contents;
     cout << "Input two values" << endl;
     fr.ptr = new int;
     is >> *(fr.ptr) >> fr.val;
     return is;
   }
   
   void SL::Erase() {
      delete(ptr);
      ptr=0;
   }
   
   int main()
   {
     cout << endl;
   
     SL l;    //  Ab0
     cin >> l;
     cout << "SL l" << " Located at " << &l << endl;
     cout << l;
     cout << endl;
        //  Ab0    A08    4   3
   
     SL m;    //  Aa0
     cin >> m;
     cout << "SL m"  << " Located at " << &m<< endl;
     cout << m;
     cout << endl;
        //  Aa0    A18    2   1
   
     l.Erase();
     m.Erase();
   
     cout << "SL l"  << " Located at " << &l<< endl;
     cout << l;
        //  Ab0    A0    ---   3
     cout << "SL m"  << " Located at " << &m<< endl;
     cout << m;
        //  Aa0    A0    ---   1
     cout << endl;
   
     return 0;
   }