#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*Napisz program z podzia³em na funkcje z parametrami, w którym u¿yjesz dwukierunkowej
listy cyklicznej do przechowywania ci¹gów znaków o d³ugoœci nieprzekraczaj¹cej 20 znaków.
Dodawanie nowych znaków nale¿y zakoñczy po tym jak u¿ytkownik wprowadzi ci¹g
„koniec”.*/


struct dll_node
{
    char data[20];
    struct dll_node *prev, *next;
};

struct dll_node *create_list(char data[20])
{
    struct dll_node *front=(struct dll_node*)malloc(sizeof(struct dll_node));
    if(front!=NULL)
    {
        front->data[20]=data;
        front->prev=front->next=NULL;
    }
    return front;
}

struct dll_node *insert_front(struct dll_node *front, struct dll_node *new_node)
{
    new_node->next=front;
    front->prev=new_node;
    return new_node;
}

void insert_back(struct dll_node *back, struct dll_node *new_node)
{
    back->next=new_node;
    new_node->prev=back;
}

void insert_after(struct dll_node *node, struct dll_node *new_node)
{
    new_node->prev=node;
    new_node->next=node->next;
    node->next->prev=new_node;
    node->next=new_node;
}

struct dll_node *find_spot(struct dll_node *front, char data[20])
{
    struct dll_node *prev=NULL;
    while((front!=NULL) && (front->data>data))
    {
        prev=front;
        front=front->next;
    }
    return prev;
}

struct dll_node *insert_node(struct dll_node *front, char data[20])
{
    if(front==NULL)
        return NULL;
    struct dll_node *new_node=(struct dll_node*)malloc(sizeof(struct dll_node));
    if(new_node!=NULL)
    {
        new_node->data[20]=data;
        new_node->prev=new_node->next=NULL;
        if(front->data<=data)
        {
            return insert_front(front,new_node);
        }
        else
        {
            struct dll_node *node=find_spot(front,data);
            if(node->next!=NULL)
            {
                insert_after(node, new_node);
            }
            else
            {
                insert_back(node, new_node);
            }
        }
    }
    return front;
}


struct dll_node *find_node(struct dll_node *front, char data[20])
{
    while((front!=NULL) && (front->data!=data))
    {
        front=front->next;
    }
    return front;
}



void remove_list(struct dll_node **front)
{
    while(*front!=NULL)
    {
        struct dll_node *next=(*front)->next;
        free(*front);
        *front=next;
    }
}

void print_list(struct dll_node *front)
{
    for(;front!=NULL;front=front->next)
    {
        printf("%s\n",front->data);
    }
    puts(" ");
}


int main(void)
{
    struct dll_node *front=create_list(0);

char input[20];

    while(1)
    {
        scanf("%s",&input);
        if(!strncmp(input,"koniec",6))
            break;
        insert_node(&(*front),input);
    }

    print_list(&(*front));
    return 0;
}