17 template <class T, size_t N> struct Array {  struct
20   T Data[N];
22   using iterator = T *;
23   using const_iterator = const T *;
25   constexpr T *data() { return Data; }  in data()
26   constexpr const T *data() const { return Data; }  in data()
28   constexpr T &front() { return Data[0]; }  in front()
29   constexpr T &front() const { return Data[0]; }  in front()
31   constexpr T &back() { return Data[N - 1]; }  in back()
32   constexpr T &back() const { return Data[N - 1]; }  in back()
38   constexpr size_t size() const { return N; }  in size()
40   constexpr bool empty() const { return N == 0; }  in empty()
42   constexpr iterator begin() { return Data; }  in begin()
43   constexpr const_iterator begin() const { return Data; }  in begin()
45   constexpr iterator end() { return Data + N; }  in end()
46   const_iterator end() const { return Data + N; }  in end()