answer.code: In function ‘int main()’:
answer.code:89:9: error: ‘ios’ has not been declared
   89 |         ios::sync_with_stdio(0), cin.tie(0);
      |         ^~~
answer.code:89:34: error: ‘cin’ was not declared in this scope; did you mean ‘std::cin’?
   89 |         ios::sync_with_stdio(0), cin.tie(0);
      |                                  ^~~
      |                                  std::cin
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:75,
                 from answer.code:1:
/usr/include/c++/11/iostream:60:18: note: ‘std::cin’ declared here
   60 |   extern istream cin;           /// Linked to standard input
      |                  ^~~
answer.code:92:9: error: ‘vector’ was not declared in this scope
   92 |         vector<pair<char, int>> a(2 * n);
      |         ^~~~~~
answer.code:92:9: note: suggested alternatives:
In file included from /usr/include/c++/11/vector:67,
                 from /usr/include/c++/11/functional:62,
                 from /usr/include/c++/11/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/11/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_vector.h:389:11: note:   ‘std::vector’
  389 |     class vector : protected _Vector_base<_Tp, _Alloc>
      |           ^~~~~~
In file included from /usr/include/c++/11/functional:62,
                 from /usr/include/c++/11/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/11/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:1:
/usr/include/c++/11/vector:86:13: note:   ‘std::pmr::vector’
   86 |       using vector = std::vector<_Tp, polymorphic_allocator<_Tp>>;
      |             ^~~~~~
answer.code:92:16: error: ‘pair’ was not declared in this scope; did you mean ‘std::pair’?
   92 |         vector<pair<char, int>> a(2 * n);
      |                ^~~~
      |                std::pair
In file included from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_pair.h:211:12: note: ‘std::pair’ declared here
  211 |     struct pair
      |            ^~~~
answer.code:92:21: error: expected primary-expression before ‘char’
   92 |         vector<pair<char, int>> a(2 * n);
      |                     ^~~~
answer.code:93:16: error: expected primary-expression before ‘int’
   93 |         vector<int> freq(n);
      |                ^~~
answer.code:94:29: error: ‘a’ was not declared in this scope
   94 |         for (auto &[c, v] : a) {
      |                             ^
answer.code:97:25: error: ‘freq’ was not declared in this scope; did you mean ‘free’?
   97 |                         freq[v]++;
      |                         ^~~~
      |                         free
answer.code:100:21: error: expected primary-expression before ‘char’
  100 |         vector<pair<char, int>> b;
      |                     ^~~~
answer.code:101:28: error: ‘a’ was not declared in this scope
  101 |         for (auto [c, v] : a) {
      |                            ^
answer.code:102:32: error: ‘freq’ was not declared in this scope; did you mean ‘free’?
  102 |                 if (v == -1 || freq[v] != 2) {
      |                                ^~~~
      |                                free
answer.code:103:25: error: ‘b’ was not declared in this scope
  103 |                         b.emplace_back(c, v);
      |                         ^
answer.code:106:9: error: ‘a’ was not declared in this scope
  106 |         a = move(b);
      |         ^
answer.code:106:18: error: ‘b’ was not declared in this scope
  106 |         a = move(b);
      |                  ^
answer.code:106:13: error: ‘move’ was not declared in this scope; did you mean ‘std::move’?
  106 |         a = move(b);
      |             ^~~~
      |             std::move
In file included from /usr/include/c++/11/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:1:
/usr/include/c++/11/pstl/glue_algorithm_defs.h:353:1: note: ‘std::move’ declared here
  353 | move(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first);
      | ^~~~
answer.code:107:15: error: expected ‘;’ before ‘f’
  107 |         vector f(a.size() + 1, vector<mint>(a.size() + 1));
      |               ^~
      |               ;
answer.code:108:9: error: ‘f’ was not declared in this scope
  108 |         f[0][0] = 1;
      |         ^
answer.code:129:26: error: ‘freq’ was not declared in this scope; did you mean ‘free’?
  129 |         int free = count(freq.begin(), freq.end(), 0);
      |                        ...