#include <stdbool.h>

typedef struct node {
    void *data;
    int key;
    node *next;
} node;

typedef struct linkedList {
    node *head;
} linkedList;

linkedList* createLinkedList();
void insertFirst(linkedList *list, int key, void *data);
node* deleteFirst(linkedList *list);
node* find(linkedList *list, int key);
node* deleteElement(linkedList *list, int key);
bool isEmpty(linkedList *list);
int length(linkedList *list);