/in/foo.cc: In function 'int main()':
/in/foo.cc:5:5: error: no match for 'operator>' (operand types are 'std::istream {aka std::basic_istream<char>}' and 'int')
  cin>n;
  ~~~^~
/in/foo.cc:5:5: note: candidate: operator>(int, int) <built-in>
/in/foo.cc:5:5: note:   no known conversion for argument 1 from 'std::istream {aka std::basic_istream<char>}' to 'int'
In file included from /usr/include/c++/6/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_pair.h:454:5: note: candidate: template<class _T1, class _T2> constexpr bool std::operator>(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
     operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^~~~~~~~
/usr/include/c++/6/bits/stl_pair.h:454:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::pair<_T1, _T2>'
  cin>n;
      ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:310:5: note: candidate: template<class _Iterator> bool std::operator>(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
     operator>(const reverse_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:310:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::reverse_iterator<_Iterator>'
  cin>n;
      ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:367:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator>(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator>(const reverse_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:367:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::reverse_iterator<_Iterator>'
  cin>n;
      ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:1161:5: note: candidate: template<class _IteratorL, class _IteratorR> bool std::operator>(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&)
     operator>(const move_iterator<_IteratorL>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1161:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::move_iterator<_IteratorL>'
  cin>n;
      ^
In file included from /usr/include/c++/6/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator.h:1167:5: note: candidate: template<class _Iterator> bool std::operator>(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorL>&)
     operator>(const move_iterator<_Iterator>& __x,
     ^~~~~~~~
/usr/include/c++/6/bits/stl_iterator.h:1167:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::move_iterator<_IteratorL>'
  cin>n;
      ^
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/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/basic_string.h:5188:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator>(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
     operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5188:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>'
  cin>n;
      ^
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/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/basic_string.h:5201:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator>(const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
     operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5201:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   'std::istream {aka std::basic_istream<char>}' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>'
  cin>n;
      ^
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/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/basic_string.h:5213:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> bool std::operator>(const _CharT*, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
     operator>(const _CharT* __lhs,
     ^~~~~~~~
/usr/include/c++/6/bits/basic_string.h:5213:5: note:   template argument deduction/substitution failed:
/in/foo.cc:5:6: note:   mismatched types 'const _CharT*' and 'std::basic_istream<char>'
  cin>n;
      ^