void ask_next(int boy_index);

void ask(int boy_index, int girl_index) {
	if (p[girl_index] == -1)
		p[girl_index] = boy_index;
	else {
		if (priority(girl_index, p[girl_index]) // O(1)
				хуже
				priority(girl_index, boy_index))
			swap(p[girl_index], boy_index);
		ask_next(boy_index); // reject
	}	
}
void ask_next(int boy_index) {
	int girl = priority_list[boy_index].pop_best();
	ask(girl);
}

// O(V+E)