/in/foo.cc:63:24: error: enclosing class of constexpr non-static member function 'bool algo::IO::isDigit(char) const' is not a literal type
         constexpr bool isDigit(const char c) const
                        ^~~~~~~
/in/foo.cc:30:11: note: 'algo::IO' is not literal because:
     class IO
           ^~
/in/foo.cc:30:11: note:   'algo::IO' has a non-trivial destructor
/in/foo.cc:68:24: error: enclosing class of constexpr non-static member function 'bool algo::IO::isDotOrDigit(char) const' is not a literal type
         constexpr bool isDotOrDigit(const char c) const
                        ^~~~~~~~~~~~
/in/foo.cc: In function 'void load()':
/in/foo.cc:196:13: warning: unused variable 'l' [-Wunused-variable]
         int l, r;
             ^
/in/foo.cc:196:16: warning: unused variable 'r' [-Wunused-variable]
         int l, r;
                ^