/in/foo.cc: In function 'int main()':
/in/foo.cc:10:29: error: no matching function for call to 'std::__cxx11::basic_string<char>::push_back(std::__cxx11::string&)'
         words.push_back(word);
                             ^
In file included from /usr/include/c++/6/string:52:0,
                 from /usr/include/c++/6/bits/locale_classes.h:40,
                 from /usr/include/c++/6/bits/ios_base.h:41,
                 from /usr/include/c++/6/ios:42,
                 from /usr/include/c++/6/istream:38,
                 from /usr/include/c++/6/sstream:38,
                 from /usr/include/c++/6/complex:45,
                 from /usr/include/c++/6/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:52,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/basic_string.h:1179:7: note: candidate: void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::push_back(_CharT) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]
       push_back(_CharT __c)
       ^~~~~~~~~
/usr/include/c++/6/bits/basic_string.h:1179:7: note:   no known conversion for argument 1 from 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' to 'char'