answer.code:12:10: error: reference to ‘data’ is ambiguous
   12 | bool cmp(data a,data b)
      |          ^~~~
In file included from /usr/include/c++/13/string:53,
                 from /usr/include/c++/13/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:52,
                 from answer.code:1:
/usr/include/c++/13/bits/range_access.h:346:5: note: candidates are: ‘template<class _Tp> constexpr const _Tp* std::data(initializer_list<_Tp>)’
  346 |     data(initializer_list<_Tp> __il) noexcept
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:336:5: note:                 ‘template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::data(_Tp (&)[_Nm])’
  336 |     data(_Tp (&__array)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:325:5: note:                 ‘template<class _Container> constexpr decltype (__cont.data()) std::data(const _Container&)’
  325 |     data(const _Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:314:5: note:                 ‘template<class _Container> constexpr decltype (__cont.data()) std::data(_Container&)’
  314 |     data(_Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
answer.code:7:8: note:                 ‘struct data’
    7 | struct data
      |        ^~~~
answer.code:12:17: error: reference to ‘data’ is ambiguous
   12 | bool cmp(data a,data b)
      |                 ^~~~
/usr/include/c++/13/bits/range_access.h:346:5: note: candidates are: ‘template<class _Tp> constexpr const _Tp* std::data(initializer_list<_Tp>)’
  346 |     data(initializer_list<_Tp> __il) noexcept
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:336:5: note:                 ‘template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::data(_Tp (&)[_Nm])’
  336 |     data(_Tp (&__array)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:325:5: note:                 ‘template<class _Container> constexpr decltype (__cont.data()) std::data(const _Container&)’
  325 |     data(const _Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
/usr/include/c++/13/bits/range_access.h:314:5: note:                 ‘template<class _Container> constexpr decltype (__cont.data()) std::data(_Container&)’
  314 |     data(_Container& __cont) noexcept(noexcept(__cont.data()))
      |     ^~~~
answer.code:7:8: note:                 ‘struct data’
    7 | struct data
      |        ^~~~
answer.code:12:23: error: expression list treated as compound expression in initializer [-fpermissive]
   12 | bool cmp(data a,data b)
      |                       ^
In file included from /usr/include/c++/13/bits/stl_algobase.h:71,
                 from /usr/include/c++/13/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:51:
/usr/include/c++/13/bits/predefined_ops.h: In instantiation of ‘constexpr bool __gnu_cxx::__ops::_Iter_comp_iter<_Compare>::operator()(_Iterator1, _Iterator2) [with _Iterator1 = data*; _Iterator2 = data*; _Compare = bool]’:
/usr/include/c++/13/bits/stl_algo.h:1819:14:   required from ‘void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = data*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]’
/usr/include/c++/13/bits/stl_algo.h:1859:25:   required from ‘void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = data*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]’
/usr/include/c++/13/bits/stl_algo.h:1950:31:   required from ‘void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = data*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]’
/usr/include/c++/13/bits/stl_algo.h:4894:18:   required from ‘void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = data*; _Compare = bool]’
answer.code:54:7:   required from here
/usr/include/c++/13/bits/predefined_ops.h:158:30: error: expression cannot be used as a function
  158 |         { return bool(_M_comp(*__it1, *__it2)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~~~
/usr/include/c++/13/bits/predefined_ops.h: In instantiation of ‘bool __gnu_cxx::__ops::_Val_comp_iter<_Compare>::operator()(_Value&, _Iterator) [with _Value = data; _Iterator = data*; _Compare = bool]’:
/usr/include/c++/13/bits/stl_algo.h:1799:20:   required from ‘void std::__unguarded_linear_insert(_RandomAccessIterator, _Compare) [with _RandomAccessIterator = data*; _Compare = __gnu_cxx::__ops::_Val_comp_iter<bool>]’
/usr/include/c++/13/bits/stl_algo.h:1827:36:   required from ‘void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = data*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<bool>]’
/usr/include/c++/13/bits/stl_algo.h:1859:25:   required from ‘void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [...