answer.code: In function ‘void dfs(long long int, long long int, long long int)’:
answer.code:31:14: error: no match for ‘operator!=’ (operand types are ‘st’ and ‘long long int’)
   31 |         if(it!=fa)dfs(it,x,d+1);
      |            ~~^~~~
      |            |   |
      |            st  long long int
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1066:5: note: candidate: ‘template<class _BiIter> bool std::__cxx11::operator!=(const std::__cxx11::sub_match<_BiIter>&, const std::__cxx11::sub_match<_BiIter>&)’
 1066 |     operator!=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1066:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   ‘st’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1146:5: note: candidate: ‘template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const std::__cxx11::sub_match<_BiIter>&)’
 1146 |     operator!=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1146:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   ‘st’ is not derived from ‘std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1239:5: note: candidate: ‘template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(const std::__cxx11::sub_match<_BiIter>&, std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)’
 1239 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1239:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   ‘st’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1313:5: note: candidate: ‘template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type*, const std::__cxx11::sub_match<_BiIter>&)’
 1313 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1313:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘long long int’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1407:5: note: candidate: ‘template<class _Bi_iter> bool std::__cxx11::operator!=(const std::__cxx11::sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)’
 1407 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1407:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   ‘st’ is not derived from ‘const std::__cxx11::sub_match<_BiIter>’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                 from answer.code:11:
/usr/include/c++/11/bits/regex.h:1481:5: note: candidate: ‘template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type&, const std::__cxx11::sub_match<_BiIter>&)’
 1481 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/regex.h:1481:5: note:   template argument deduction/substitution failed:
answer.code:31:16: note:   mismatched types ‘const std::__cxx11::sub_match<_BiIter>’ and ‘long long int’
   31 |         if(it!=fa)dfs(it,x,d+1);
      |                ^~
In file included from /usr/include/c++/11/regex:63,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:110,
                ...