/in/foo.cc: In function 'std::istream& operator>>(std::istream&, const Matrix3&)':
/in/foo.cc:55:19: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and 'const int')
   55 |                 in>>other.v[i][j];
      |                 ~~^~~~~~~~~~~~~~~
      |                 |               |
      |                 |               const int
      |                 std::istream {aka std::basic_istream<char>}
In file included from /usr/include/c++/12/iostream:40,
                 from /in/foo.cc:1:
/usr/include/c++/12/istream:120:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  120 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/12/istream:120:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: invalid conversion from 'int' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'} [-fpermissive]
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
      |                                 |
      |                                 int
/usr/include/c++/12/istream:124:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]' (near match)
  124 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/12/istream:124:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: invalid conversion from 'int' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&)' {aka 'std::basic_ios<char>& (*)(std::basic_ios<char>&)'} [-fpermissive]
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
      |                                 |
      |                                 int
/usr/include/c++/12/istream:131:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  131 |       operator>>(ios_base& (*__pf)(ios_base&))
      |       ^~~~~~~~
/usr/include/c++/12/istream:131:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: invalid conversion from 'int' to 'std::ios_base& (*)(std::ios_base&)' [-fpermissive]
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
      |                                 |
      |                                 int
/usr/include/c++/12/istream:168:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  168 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:168:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:172:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  172 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/12/istream:172:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:175:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  175 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:175:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:179:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  179 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/12/istream:179:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: binding reference of type 'int&' to 'const int' discards qualifiers
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:182:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  182 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:182:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:186:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  186 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:186:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:190:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  190 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:190:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:195:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  195 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/12/istream:195:7: note:   conversion of argument 1 would be ill-formed:
/in/foo.cc:55:33: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type 'int'
   55 |                 in>>other.v[i][j];
      |                     ~~~~~~~~~~~~^
/usr/include/c++/12/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_tr