#include <iostream>

using namespace std;

class Node

{

public:

int data;

Node* next;

Node(int data){

this->data=data;

next=NULL;

}

};

//stack using linked list

class Stack

{

Node* head;

int Size; //for calculating size of stack

public:

//constructor

Stack()

{

head=NULL;

Size=0;

}

//getSize function

int getSize()

{

return Size;

}

bool isEmpty()

{

if(head==NULL)

return true;

else

return false;

}

void push(int element)

{

Node* newNode = new Node(element);

newNode->next = head;

head=newNode;

Size++;

}

int pop()

{

if(isEmpty())

return 0;

int ans = head->data;

Node* temp = head;

head=head->next;

delete temp;

Size--;

return ans;

}

int top()

{

if(isEmpty())

return 0;

return head->data;

}

};

int main()

{

cout<<"Program started.."<<endl;

Stack s;

s.push(12);

s.push(13);

s.push(14);

s.push(15);

s.push(16);

cout<<"top of stack is: "<<s.top()<<endl;

cout<<"is stack empty: "<<s.isEmpty()<<endl;

cout<<"element popped: "<<s.pop()<<endl;

cout<<"size of stack is: "<<s.getSize()<<endl;

cout<<"top of stack is: "<<s.top()<<endl;

return 0;

}