pthread_mutex_t t1= PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t t2= PTHREAD_MUTEX_INITIALIZER;
void first(function<void()> printFirst) {
// printFirst() outputs "first". Do not change or remove this line.
pthread_mutex_unlock(&t1);
void second(function<void()> printSecond) {
// printSecond() outputs "second". Do not change or remove this line.
pthread_mutex_unlock(&t2);
void third(function<void()> printThird) {
// printThird() outputs "third". Do not change or remove this line.