c언어 stack

#include<iostream>
using namespace std;
 
struct Node
{
    int data;
    Node* next;
}*top=NULL;
 
void push(int x)
{
    Node* t;
    t = new Node;
 
    if (t == NULL)
        cout << "stack is full";
    else
    {
        t->data = x;
        t->next = top;
        top = t;
    }
}
int pop()
{
    Node* t;
    int x = -1;
    if (top == NULL)
        cout << "empty";
    else
    {
        t = top;
        top = top->next;
        x = t->data;
        delete t;
    }
    return x;
}
void Display()
{
    Node* p;
    p = top;
    while (p)
    {
        cout << p->data<< " ";
        p = p->next;
    }
}
 
int main()
{
    push(10);
    push(20);
    push(30);
 
    pop();
    Display();
    return 0;
}