void delete_linked_list(Node *head){
Node *p = head;
Node *q = NULL;
while (p != NULL){
q = p->next;
free(p);
p = q;
}
}
void delete_linked_list(Node *head){
Node *p = head;
Node *q = NULL;
while (p != NULL){
q = p->next;
free(p);
p = q;
}
}