answer.code:4:1: error: extended character 。 is not valid in an identifier
    4 | 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
      | ^
answer.code:4:1: error: extended character 。 is not valid in an identifier
answer.code:1:1: error: ‘作者：GhostLX’ does not name a type
    1 | 作者：GhostLX
      | ^~~~~~~~~~~~~
In file included from /usr/include/c++/11/cmath:43,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/include/c++/11/ext/type_traits.h:162:35: error: ‘bool __gnu_cxx::__is_null_pointer’ redeclared as different kind of entity
  162 |   __is_null_pointer(std::nullptr_t)
      |                                   ^
/usr/include/c++/11/ext/type_traits.h:157:5: note: previous declaration ‘template<class _Type> bool __gnu_cxx::__is_null_pointer(_Type)’
  157 |     __is_null_pointer(_Type)
      |     ^~~~~~~~~~~~~~~~~
/usr/include/c++/11/ext/type_traits.h:162:26: error: ‘nullptr_t’ is not a member of ‘std’
  162 |   __is_null_pointer(std::nullptr_t)
      |                          ^~~~~~~~~
In file included from /usr/include/c++/11/bits/move.h:57,
                 from /usr/include/c++/11/bits/stl_pair.h:59,
                 from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/include/c++/11/type_traits:405:26: error: ‘std::size_t’ has not been declared
  405 |   template<typename _Tp, std::size_t _Size>
      |                          ^~~
/usr/include/c++/11/type_traits:406:25: error: ‘_Size’ was not declared in this scope
  406 |     struct is_array<_Tp[_Size]>
      |                         ^~~~~
/usr/include/c++/11/type_traits:406:31: error: template argument 1 is invalid
  406 |     struct is_array<_Tp[_Size]>
      |                               ^
/usr/include/c++/11/type_traits:511:42: error: ‘nullptr_t’ is not a member of ‘std’
  511 |     struct __is_null_pointer_helper<std::nullptr_t>
      |                                          ^~~~~~~~~
/usr/include/c++/11/type_traits:511:51: error: template argument 1 is invalid
  511 |     struct __is_null_pointer_helper<std::nullptr_t>
      |                                                   ^
/usr/include/c++/11/type_traits:1311:37: error: ‘size_t’ is not a member of ‘std’; did you mean ‘size_t’?
 1311 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/11/bits/std_abs.h:38,
                 from /usr/include/c++/11/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/lib/gcc/x86_64-linux-gnu/11/include/stddef.h:209:23: note: ‘size_t’ declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/11/bits/move.h:57,
                 from /usr/include/c++/11/bits/stl_pair.h:59,
                 from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/include/c++/11/type_traits:1311:57: error: template argument 1 is invalid
 1311 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                                         ^
/usr/include/c++/11/type_traits:1320:37: error: ‘size_t’ is not a member of ‘std’; did you mean ‘size_t’?
 1320 |     : public integral_constant<std::size_t, 0> { };
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/11/bits/std_abs.h:38,
                 from /usr/include/c++/11/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/lib/gcc/x86_64-linux-gnu/11/include/stddef.h:209:23: note: ‘size_t’ declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/11/bits/move.h:57,
                 from /usr/include/c++/11/bits/stl_pair.h:59,
                 from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:6:
/usr/include/c++/11/type_traits:1320:46: error: template argument 1 is invalid
 1320 |     : public integral_constant<std::size_t, 0> { };
      |                                              ^
/usr/include/c++/11/type_traits:1322:26: error: ‘std::size_t’ has not been d...