#include <stdio.h>
#include <stdlib.h>
struct node 
{
    int info;
    struct node *link;
};
typedef struct node* NODE;
NODE insert_rear(int ,NODE );
NODE delete_front(NODE );
void display(NODE );
int main()
{
    int ch,item;
    NODE first;
    first=NULL;
    while(1)
    {
        scanf("%d",&ch);
        switch (ch)
        {
            case 1:
                scanf("%d",&item);
                first=insert_rear(item,first);
                break;
            case 2:
                first=delete_front(first);
                break;
            case 3:
                display(first);
                break;
            case 4:exit(0);
            default:
                printf("Invalid Choice");
        }
    }
}
NODE insert_rear(int item,NODE first)
{
    NODE temp,cur;
    temp=(struct node*)malloc(1*sizeof(struct node));
    temp->info=item;
    temp->link=NULL;
    if(first==NULL)
    {
        return temp;
    }
    cur=first;
    while(cur->link!=NULL)
    {
        cur=cur->link;
    }
    cur->link=temp;
    return first;
}
NODE delete_front(NODE first)
{
    NODE temp;
    if(first==NULL)
    {
        printf("\nQUEUE UNDERFLOW - No nodes to delete\n");
        return NULL;
    }
    temp=first;
    first=first->link;
    printf("\nThe DEQUEUED Node VAL = %d",temp->info);
    free(temp);
    return first;
}
void display(NODE first)
{
    NODE temp=first;
    if(first==NULL)
    {
        printf("\nEmpty QUEUE - NOTHING TO DISPLAY");
        return;
    }
    printf("\nTHE ELEMENTS OF QUEUE ARE -\n");
    while(temp!=NULL)
    {
        printf("%d ",temp->info);
        temp=temp->link;
        printf(" ->");
    }
}