answer.code:19:8: error: elements of array ‘Matrix power [32]’ have incomplete type
   19 | Matrix power[LG];
      |        ^~~~~
answer.code:19:8: error: storage size of ‘power’ isn’t known
answer.code:21:25: error: ‘A’ has incomplete type
   21 | Vector multiply (Matrix A, Vector B) {
      |                  ~~~~~~~^
In file included from /usr/include/c++/13/bits/stl_map.h:63,
                 from /usr/include/c++/13/map:63,
                 from answer.code:3:
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘Matrix’ {aka ‘struct std::array<std::array<long long int, 49>, 49>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:21:35: error: ‘B’ has incomplete type
   21 | Vector multiply (Matrix A, Vector B) {
      |                            ~~~~~~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘Vector’ {aka ‘struct std::array<long long int, 49>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:21:36: error: return type ‘Vector’ {aka ‘struct std::array<long long int, 49>’} is incomplete
   21 | Vector multiply (Matrix A, Vector B) {
      |                                    ^
answer.code: In function ‘void multiply(Matrix, Vector)’:
answer.code:22:10: error: aggregate ‘Vector C’ has incomplete type and cannot be defined
   22 |   Vector C;
      |          ^
answer.code: At global scope:
answer.code:30:25: error: ‘A’ has incomplete type
   30 | Matrix multiply (Matrix A, Matrix B) {
      |                  ~~~~~~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘Matrix’ {aka ‘struct std::array<std::array<long long int, 49>, 49>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:30:35: error: ‘B’ has incomplete type
   30 | Matrix multiply (Matrix A, Matrix B) {
      |                            ~~~~~~~^
/usr/include/c++/13/tuple:2005:45: note: declaration of ‘Matrix’ {aka ‘struct std::array<std::array<long long int, 49>, 49>’}
 2005 |   template<typename _Tp, size_t _Nm> struct array;
      |                                             ^~~~~
answer.code:30:36: error: return type ‘Matrix’ {aka ‘struct std::array<std::array<long long int, 49>, 49>’} is incomplete
   30 | Matrix multiply (Matrix A, Matrix B) {
      |                                    ^
answer.code: In function ‘void multiply(Matrix, Matrix)’:
answer.code:31:10: error: aggregate ‘Matrix C’ has incomplete type and cannot be defined
   31 |   Matrix C;
      |          ^
answer.code: In function ‘int main()’:
answer.code:42:10: error: aggregate ‘Matrix base’ has incomplete type and cannot be defined
   42 |   Matrix base;
      |          ^~~~
answer.code:70:12: error: aggregate ‘Vector result’ has incomplete type and cannot be defined
   70 |     Vector result;
      |            ^~~~~~