View Compilation Error

0_0_1937138_31854.cpp: In function `int main()':
0_0_1937138_31854.cpp:7: error: ambiguous overload for 'operator>>' in '(&std::cin)->std::basic_istream<_CharT, _Traits>::operator>> [with _CharT = char, _Traits = std::char_traits<char>](((double&)(&x1))) >> " "'
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/istream:687: note: candidates are: std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*) [with _Traits = std::char_traits<char>] <near match>
GCC/bin/../lib/gcc/mingw32/3.4.2/../../../../include/c++/3.4.2/istream:692: note:                 std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*) [with _Traits = std::char_traits<char>] <near match>