foo.cc: In function ‘int Count(std::string)’:
foo.cc:7:29: error: invalid use of member function ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::length() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]’ (did you forget the ‘()’ ?)
    7 |         for(int i=0;i<int(s.length);i++)
      |                           ~~^~~~~~
      |                                   ()