View Compilation Error

1_645_2919_4575.cpp: In function 'void bfs(int, long long int*)':
1_645_2919_4575.cpp:29:14: error: cannot convert 'std::queue<_Tp, _Sequence>::empty<int, std::deque<int, std::allocator<int> > >' from type 'bool (std::queue<int>::)() const' to type 'bool'
  while (!que.empty)
              ^
1_645_2919_4575.cpp:29:14: error: in argument to unary !