typedef struct Node
{
  int data;
  struct Node* next;
}node, *pLinkedlist;
void printCommomElem(pLinkedlist head1, pLinkedlist head2)
{
  cout << "print commom elements: " << endl;
  while (head1->next != NULL && head2->next != NULL)
  {
    if (head1->data < head2->data)
      head1 = head1->next;
    else if (head1->data > head2->data)
      head2 = head2->next;
    else
    {
      cout << head1->data << " ";
      head1 = head1->next;
      head2 = head2->next;
    }
  }
  cout << endl;
}