#include <assert.h>
#include <iostream.h>
//#include <bool.h>

class Istack {
	int sz;
	int top;
	int* stack;
public:
	Istack(void) { sz = 97; stack = new int[sz]; top = sz; 
				cout << "using default creator 97\n";}
	Istack(int Nitems )	// The creators
		{ sz = Nitems; stack = new int[sz]; top = sz; 
				cout << "using pre-set creator " << Nitems << "\n"; }
	~Istack() { delete[] stack; } 
					// delete[] removes array space
	void push(int x) { assert( !isfull() ); 
						stack[--top] = x; }
	int pop() { assert( !isempty() ); 
						return( stack[top++] ); }
	bool isempty() { return( top == sz ); }
	bool isfull() { return( top == 0); }
};