слияние хз

#include<iostream>
#include<string>

using namespace std;

struct ListElem
{
   int value;
   ListElem *next;
};

class SortedList
{
  ListElem *pbeg, *pend;
   void push_back(ListElem *ptr);
   ListElem *pop_front();
   int Size;
public:
   SortedList() { pend = pbeg = NULL; }
   void merge(SortedList &lst);
   void sort(SortedList );
   int pop_front_type();
   void push_front(int val);
   int get_Size() {return Size;};
};

ListElem *SortedList::pop_front()
{
   if (pbeg == 0)
    return NULL;
   ListElem *ptr = pbeg;
   pbeg = pbeg->next;
   if (pbeg == 0)
    pend = NULL;
   return ptr;
}

void SortedList::push_back(ListElem *ptr)
{
   ptr->next = NULL;
   if (pbeg == 0)
    pbeg = pend = ptr;
   else
   {
    pend->next = ptr;
    pend = ptr;
    }
}

void SortedList::push_front(int val)
{
   ListElem *pnew = new ListElem;
   pnew->value = val;
   pnew->next = pbeg;
   pbeg = pnew;
   if (!pend)
     pend = pnew;
  Size++;
}

int SortedList::pop_front_type()
{
   if (!pbeg)
   return -1;
   ListElem *ptr = pbeg;
   int val = pbeg->value;
   pbeg = pbeg->next;
   if (!pbeg)
    pend = NULL;
   delete ptr;
   return val;
}

void SortedList::merge(SortedList& B)
{
  if (!B.pbeg)
   return;
  if (!pbeg)
  {
    pbeg = B.pbeg;
    pend = B.pend;
    B.pbeg = B.pend = NULL;
  }
  else
  {
    SortedList C;
    ListElem *ptr;
    while (pbeg != 0 || B.pbeg != 0)
    {
      if (B.pbeg == 0)
       ptr = pop_front();
      else if (pbeg == 0)
       ptr = B.pop_front();
      else if (pbeg->value <= B.pbeg->value)
        ptr = pop_front();
      else ptr = B.pop_front();
       C.push_back(ptr);
    }
    pbeg = C.pbeg;
    pend = C.pend;
    C.pbeg = C.pend = NULL;
  }
}

int main()
{
 SortedList lst;
  int number, n;

 for (int i = 0; i<n; i++)
    {
      cin >> number;
      lst.push_front(number);
    }

   lst.merge(lst);

  int dlina = lst.get_Size();

  int *arr = new int[dlina];

  for (int i = 0; i < dlina; i++)
   arr[i] = lst.pop_front_type();

   for (int i = dlina - 1; i >= 0; i--)
    cout << arr[i] << " ";
}