#include <iostream>
#include <time.h>
#include <cstdlib>

using namespace std;

struct element
{
    int number;
    element* next;
};

struct single_list
{
    element* head;
    element* tail;
    int counter;
};

void show_single_list(single_list q) {
    element* iterator = q.head;
    while (iterator != nullptr) {
        cout << iterator->number << " ";
        iterator = iterator->next;
    }
    cout << endl;
}

void add_tail(single_list& l, int value)
{
    element* el;
    el = new element;
    el->number = value;
    el->next = nullptr;
    if (l.tail != nullptr)
        l.tail->next = el;
    else
        l.head = el;
    l.tail = el;
    l.counter++;
}
void add_head(single_list& l, int value)
{
    element* el;
    el = new element;
    el->number = value;
    el->next = l.head;
    l.head = el;
    if (l.tail == nullptr)
    {
        l.tail = el;
    }
    l.counter++;
}
void z2(single_list &l)
{
    int liczbarandom=1;
    while (liczbarandom != 0)
    {
        liczbarandom =(rand() % 40) - 20;
        if (liczbarandom < 0)
        {
            add_head(l, liczbarandom);
        }
        if (liczbarandom > 0)
        {
            add_tail(l, liczbarandom);
        }
    }
    show_single_list(l);
}
int main()
{
    srand(time(NULL));
    single_list l;
    l.head = nullptr;
    l.tail = nullptr;
    z2(l);
    return 0;
}