stack using link list

#include<iostream>
using namespace std;
struct node
{
int data;
node *next;
};
class stack
{
public:
node *p=NULL,*q,*t;
void push(int d);
int pop();
};
void stack::push(int d)
{
if(p==NULL)
{
p=new(node);
p->data=d; p->next=NULL;
}
else
{
t=new(node);
t->data=d;
t->next=p;
p=t;
}
}
int stack:: pop()
{
int a;
if(p!=NULL)
{
    a=p->data;
p=p->next;
return a;
}
}
int main()
{ stack s;
int i,j,n;
cout<<"enter 4 no";
for(i=0;i<4;i++)
{
cin>>n;
s.push(n);
}
cout<<"in reverse ";

for(i=0;i<4;i++)
{

cout<<s.pop();
}
return 0;
}