/in/foo.cc: In function 'int main()':
/in/foo.cc:29:18: error: 'endl' was not declared in this scope
  std::cout<<ans<<endl;
                  ^~~~
/in/foo.cc:29:18: note: suggested alternative:
In file included from /usr/include/c++/6/istream:39:0,
                 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/ostream:590:5: note:   'std::endl'
     endl(basic_ostream<_CharT, _Traits>& __os)
     ^~~~