#include <iostream>
using namespace std;

void menu(){
cout << "Choose one of options" << endl;
cout << "1. New queue" << endl;
cout << "2. Attach" << endl;
cout << "3. Delete" << endl;
cout << "4. Print" << endl;
cout << "5. End" << endl;
}

struct el_FIFO {
int x;
struct el_FIFO *nast;
};

struct FIFO {
struct el_FIFO *front;
struct el_FIFO *rear;
};

void attach(struct FIFO *k, int el){
struct el_FIFO *nowy = new el_FIFO;
nowy->x = el;
nowy->nast = NULL;
if (k->front == NULL)
{
    k->front = nowy;
    k->rear = nowy;
}
else {
    k->rear->nast = nowy;
    k->rear = nowy;
}
}

void del(struct FIFO *k){
struct el_FIFO *temp;
if (k->front!= NULL){
    temp = k->front->nast;
    delete k->front;
    k->front = temp;
}
else{
    cout << "There is no element to delete";
}
}

void new_queue(struct FIFO *k){
if (k->front == NULL){
    cout << "queue is already empty";
}
else{
    while (k->front != NULL){
        del(k);
    }
    cout << "queue is empty";

}
}

void print(struct FIFO *k){
struct FIFO *temp_FIFO;
if(k->front){
    cout << "queue: " << endl;
    while(k->front){
        if (temp_FIFO->front == NULL){
            temp_FIFO->front = k->front;
            temp_FIFO->rear = k->front;
        }
        else{
            temp_FIFO->rear->nast = k->front;
            temp_FIFO->rear = k->front;
        }
        cout << k->front->x << endl;
        del(k);
    }
    while(temp_FIFO->front){
        if (k->front == NULL){
            k->front = temp_FIFO->front;
            k->rear = temp_FIFO->front;
        }
        else{
            k->rear->nast = temp_FIFO->front;
            k->rear = temp_FIFO->front;
        }
        del(temp_FIFO);
    }
}
else{
    cout << "queue is empty";
}
}

int rear(){
cout << "The end";
return 0;
}

int main()
{
struct FIFO *queue = new FIFO;
queue->front = NULL;
queue->rear = NULL;
int el=0;
int c=0;
do{
menu();
cin >> c;
cout << endl;
switch (c)
{
case 1: new_queue(queue);
        cout << endl << endl;
    break;
case 2: cout << "Add element" << endl;
        cin >> el;
        attach (queue, el);
        cout << endl;
    break;
case 3: cout << "Element will be deleted" << endl;
        del(queue);
        cout << endl << endl;
    break;
case 4: print(queue);
        cout << endl;
    break;
case 5: rear();
    break;
default: cout << "You chose wrong" << endl << endl;
    break;
}
} while (c!=5);
return 0;
}