#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

struct ListItem
{
    struct ListItem *prev, *next;
    uint64_t value;
};

struct List
{
    struct ListItem *first, *last;
};

struct ListItem *to_front(struct List *lst, uint64_t value, size_t maxsize) ;
int main(int argc, char **argv) {
    struct List lst;
    lst.first = NULL;
    lst.last = NULL;
    to_front(&lst, 4, 10);
    to_front(&lst, 3, 10);
    to_front(&lst, 2, 10);
    to_front(&lst, 1, 10);
    to_front(&lst, 5, 3);
    struct ListItem *current = lst.first;
    while (current) {
        printf("%ld\n", current->value);
        current = current->next;
    }
    printf("\n");
    current = lst.last;
    while (current) {
        printf("%ld\n", current->value);
        current = current->prev;
    }
    return 0;
 }