#include <iostream>
#include <cstring>
 
using namespace std;
 
 
struct Task {
    void* next;
    bool active;
    char* title;
};
 
Task* first;
 
Task* addTask(const char* title) {
    Task* t = first;
    while (t != NULL && t->active != false && t->next != NULL) t = (Task*) t->next;
    if (t->active == true) {
        t->next = (void*) malloc(sizeof(Task));
        t = (Task*) t->next;
    }
    free(t->title);
    t->active = true;
    t->title = (char*) malloc(strlen(title)+sizeof(char));
    memcpy(t->title, title, strlen(title));
    return t;
}
 
void destroy_tasks(Task* first) {
    Task* next = (Task*) first->next;
    free(first->title);
    free(first);
    first = NULL;
    if (next != NULL) {
        destroy_tasks(next);
    }
}
 
int main()
{
    first = (Task*) malloc(sizeof(Task));
    first->next = NULL;
 
    addTask("Hello world");
    addTask("Hello univerce");
    addTask("Hello Enigma");
 
    Task* t = first;
    while (t != NULL) {
        if (t->active) {
            cout << t->title << endl;
        }
        t = (Task*) t->next;
    }
 
    destroy_tasks(first);
 
    cout << "end" << endl;
    return 0;
}