смена элементов местами

#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 change (int znach_1, int znach_2);
   int top();
};

ListElem* List::find_elem(int keyval)
{
   ListElem *pcur = pbeg;
   for (; pcur; pcur = pcur->next)
    if (pcur->value == keyval)
      break;
   return pcur;
}

bool List::change(int znach_1, int znach_2)
{
  ListElem *ptr_1, *ptr_2;
  ptr_1 = find_elem(znach_1);
  ptr_2 = find_elem(znach_2);

  ptr_1->value = znach_2;
  ptr_2->value = znach_1;
  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_1, znach_2;

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

  int dlina = lst.get_Size();

  znach_1 = lst.pop_front();
  znach_2 = lst.pop_front();

  lst.change(znach_1, znach_2);

  dlina -= 2;

  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] << " ";
}