In file included from /usr/include/c++/6/iostream:38:0,
                 from /in/foo.cc:17:
/usr/include/c++/6/sstream: In function 'int main()':
/usr/include/c++/6/sstream:41:15: error: expected '=' before '__attribute__'
 namespace std _GLIBCXX_VISIBILITY(default)
               ^
/usr/include/c++/6/sstream:41:15: error: expected identifier before '__attribute__'
/usr/include/c++/6/sstream:41:15: error: expected ';' before '__attribute__'
/usr/include/c++/6/sstream:41:15: error: expected primary-expression before '__attribute__'
/usr/include/c++/6/bits/sstream.tcc:39:15: error: expected '=' before '__attribute__'
 namespace std _GLIBCXX_VISIBILITY(default)
               ^
/usr/include/c++/6/bits/sstream.tcc:39:15: error: expected identifier before '__attribute__'
/usr/include/c++/6/bits/sstream.tcc:39:15: error: expected ';' before '__attribute__'
/usr/include/c++/6/bits/sstream.tcc:39:15: error: expected primary-expression before '__attribute__'
/in/foo.cc:39:15: error: expected unqualified-id before '<<' token
  ostringstream<<fixed<<setprecision(2)<<bill;
               ^~
/in/foo.cc:40:26: error: expected primary-expression before '.' token
  string ans=ostringstream.str();
                          ^