вставка элемента

#include <iostream>
using namespace std;

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

class List
{
   ListElem *pbeg, *pend;
   ListElem *find_elem(int keyval);
   int Size = 0;
public:
   List() {  pend = pbeg = NULL; }
   int get_Size() { return Size; }
   void push_front(int val);
   int pop_front();
   bool insert(int val, int znach);
   int top();
};

ListElem* List::find_elem(int keyval)
{
   ListElem *pcur = pbeg;
   int shet = 0;
   for (; pcur; pcur = pcur->next)
    {
      shet++;
      if (shet == keyval)
      goto printl;
    }
   printl:
   return pcur;
}

bool List::insert(int val, int znach)
{
  ListElem *ptr = find_elem(val);
   if (!ptr) return false;
   ListElem *pnew = new ListElem;
   pnew->value = znach;
   pnew->next = ptr->next;
   ptr->next = pnew;
   return true;
}

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

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

int main ()
{
  List lst;
  int number, znach, index, n;
  //cin >> n;

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


  int dlina = lst.get_Size();

  index = dlina - lst.pop_front() - 1;
  znach = lst.pop_front();

  if (index == 0)
   lst.push_front(znach);
  else
    lst.insert(index, znach);
    dlina--;

  int *arr = new int[dlina];

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

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