/in/foo.cc: In function 'int main()':
/in/foo.cc:5:2: error: 'string' was not declared in this scope
  string s;
  ^~~~~~
/in/foo.cc:5:2: note: suggested alternatives:
In file included from /usr/include/c++/6/iosfwd:39:0,
                 from /usr/include/c++/6/ios:38,
                 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/stringfwd.h:74:33: note:   'std::__cxx11::string'
   typedef basic_string<char>    string;
                                 ^~~~~~
/usr/include/c++/6/bits/stringfwd.h:74:33: note:   'std::__cxx11::string'
/in/foo.cc:6:5: error: 'cin' was not declared in this scope
     cin>>s;
     ^~~
/in/foo.cc:6:5: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:75:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
/in/foo.cc:6:10: error: 's' was not declared in this scope
     cin>>s;
          ^
/in/foo.cc:7:2: error: 'cout' was not declared in this scope
  cout<<s;
  ^~~~
/in/foo.cc:7:2: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:75:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~