answer.code:149:15: error: ‘A’ has incomplete type
  149 | P operator-(P A, P B){
      |             ~~^
In file included from /usr/include/c++/13/bits/stl_map.h:63,
                 from /usr/include/c++/13/map:63,
                 from answer.code:6:
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:149:20: error: ‘B’ has incomplete type
  149 | P operator-(P A, P B){
      |                  ~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:149:21: error: return type ‘P’ {aka ‘struct std::array<int, 3>’} is incomplete
  149 | P operator-(P A, P B){
      |                     ^
answer.code:152:11: error: ‘A’ has incomplete type
  152 | P Cross(P A, P B){
      |         ~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:152:16: error: ‘B’ has incomplete type
  152 | P Cross(P A, P B){
      |              ~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:152:17: error: return type ‘P’ {aka ‘struct std::array<int, 3>’} is incomplete
  152 | P Cross(P A, P B){
      |                 ^
answer.code:155:10: error: ‘A’ has incomplete type
  155 | ll Dot(P A, P B){
      |        ~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:155:15: error: ‘B’ has incomplete type
  155 | ll Dot(P A, P B){
      |             ~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘P’ {aka ‘struct std::array<int, 3>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:158:3: error: aggregate ‘P zero’ has incomplete type and cannot be defined
  158 | P zero;
      |   ^~~~
answer.code:160:3: error: elements of array ‘P po [1010]’ have incomplete type
  160 | P po[N];
      |   ^~
answer.code:160:3: error: storage size of ‘po’ isn’t known
answer.code: In function ‘int main()’:
answer.code:180:19: error: variable ‘P V’ has initializer but incomplete type
  180 |                 P V = Cross(po[j] - po[i], po[k] - po[i]);
      |                   ^
In file included from /usr/include/c++/13/bits/stl_algobase.h:64,
                 from /usr/include/c++/13/string:51,
                 from /usr/include/c++/13/bits/locale_classes.h:40,
                 from /usr/include/c++/13/bits/ios_base.h:41,
                 from /usr/include/c++/13/ios:44,
                 from /usr/include/c++/13/ostream:40,
                 from /usr/include/c++/13/iostream:41,
                 from answer.code:1:
/usr/include/c++/13/bits/stl_pair.h: In instantiation of ‘struct std::pair<std::array<int, 3>, long long int>’:
answer.code:190:19:   required from here
/usr/include/c++/13/bits/stl_pair.h:193:11: error: ‘std::pair<_T1, _T2>::first’ has incomplete type
  193 |       _T1 first;                 ///< The first member
      |           ^~~~~
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘struct std::array<int, 3>’
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
In file included from /usr/include/c++/13/bits/move.h:37,
                 from /usr/include/c++/13/bits/exception_ptr.h:41,
                 from /usr/include/c++/13/exception:164,
                 from /usr/include/c++/13/ios:41:
/usr/include/c++/13/type_traits: In instantiation of ‘struct std::is_copy_assignable<std::array<int, 3> >’:
/usr/include/c++/13/type_traits:161:35:   required by substitution of ‘template<class ... _Bn> std::__detail::__first_t<std::integral_constant<bool, true>, typename std::enable_if<(bool)(_Bn::value), void>::type ...> std::__detail::__and_fn(int) [with _Bn = {std::is_copy_assignable<std::array<int, 3> >, std::is_copy_assignable<long long int>}]’
/usr/include/c++/13/type_traits:177:42:   required from ‘struct std::__and_<std::is_copy_assignable<std::array<int, 3> >, std::is_copy_assignable<long long int> >’
/usr/include/c++/13/bits/stl_pair.h:727:7:   required from ‘struct std::pair<std::array<int, 3>, long long int>’
answer.code:190:19:   required from here
/usr/include/c++/13/type_traits:1167:52: error: static assertion failed: template argument must be a complete class or an unbounded array
 1167 |       static_assert(std::__is_complete_o...