class IntListStack {
private:

  class SNode {
  public:
    SNode (int data, SNode *next) {
      this -> data = data; this -> next = next;
    }
    int data;
    SNode *next;
  };

  SNode *head; // head pointer for the linked list
  bool elastic; // true if stack is elastic (has infinite capacity)
  int capacity; // stack capacity (only meaningful if "elastic" is false)

  int count; // number of values on stack

public:

  // creates an "elastic" stack
  IntListStack ();

  // creates a stack with a fixed capacity
  IntListStack (int capacity);

  IntListStack (const IntListStack &otherStack);

  ~IntListStack ();

  // throws an "overflow_error" exception if the stack has a fixed
  // capacity and is full.
  void push (int value);

  // throws an "overflow_error" exception if the stack is empty
  int pop ();

  bool isEmpty() const { return count == 0; }

  int getcount() const { return count; }

  // copies contents only (capacity attributes are not copied).
  // throws an "overflow_error" exception if the destination stack
  // has a fixed capacity and this is not large enough.
  IntListStack& operator= (const IntListStack &otherStack);

};