Pls help me to finish a project i dont know how i can free this struct.
When i use valgrind it says memory lost because i dont know ho to use free

```
typedef struct list{
    int value1;
    int value2;
    struct list * next;
}List;

List *first;
List *last;

void create_list(){
    List *aux;
    aux = (List *) malloc(sizeof(List));
    first= aux;
    last= first;
}     

void insert(int a, int b){
    List *aux;
    aux = (List *) malloc(sizeof(List));
    aux->value1=a;
    aux->value2=b;
    last->next=aux;
    last= last->next;
    aux->next= NULL;
}

int main(int argc, const char* argv[]){

    create_list();
    insert(1,2);

    //How can i free?

}

```