struct item {
    int key;
    int data;
    struct item *next;
};

static struct item *head = NULL;


void init()
{
    head = NULL;
}


void printall()
{
    struct item *p;
    for (p = head; p; p = p->next)
        printf("%d: %d\n", p->key, p->data);
}


int search(int key)
{
    struct item *it, *prev;

    for (it = head; it && it->key < key; it = it->next)
        prev = it;
    if (it && it->key == key)
        return it->data;
    else
        return -1;
}