/in/foo.cc: In function 'int main()':
/in/foo.cc:44:61: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::priority_queue<int>::size_type {aka long unsigned int}' [-Wformat=]
 printf("%d",q.size/*返回优先队列中的元素个数*/());
                                                             ^