#include <iostream>

struct frame {
    int data;
    frame *next;
};

struct stack {
    int size;
    frame *head;
};


void initialize(stack *stk){
    stk->size = 0;
    stk->head = nullptr;
}

void push(stack *stk, int number) {
    frame frm = {number, stk->head};
    std::cout << "push" << frm.data << std::endl;
    stk->size += 1;
    stk->head = &frm;
}

int pop(stack *stk) {
    if (stk->size == 0) throw std::runtime_error("underflow");
    int value = stk->head->data;
    stk->size -= 1;
    stk->head = stk->head->next;
    return value;
}


int main() {
    stack *stk;
    initialize(stk);
    std::cout<<"test";
    push(stk, 5);
    push(stk, 3);
    std::cout << "Pop" << pop(stk) << std::endl;

    return 0;
}