Borderou de evaluare (job #373128)

Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:23:16: error: no match for ‘operator=’ in ‘in.std::basic_ifstream<char>::<anonymous>.std::basic_istream<_CharT, _Traits>::operator>> [with _CharT = char, _Traits = std::char_traits<char>]((* & r)) = std::sqrt [with _Tp = int, typename __gnu_cxx::__enable_if<std::__is_integer<_Tp>::__value, double>::__type = double](a)’ user.cpp:23:16: note: candidate is: /usr/include/c++/4.6/istream:57:11: note: std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&) <deleted> /usr/include/c++/4.6/istream:57:11: note: no known conversion for argument 1 from ‘__gnu_cxx::__enable_if<true, double>::__type {aka double}’ to ‘const std::basic_istream<char>&’ user.cpp: At global scope: user.cpp:30:5: error: expected unqualified-id before ‘return’