answer.code: In function ‘int main()’:
answer.code:14:5: error: ‘nordered_set’ was not declared in this scope
   14 |     nordered_set<int> st;
      |     ^~~~~~~~~~~~
answer.code:14:18: error: expected primary-expression before ‘int’
   14 |     nordered_set<int> st;
      |                  ^~~
answer.code:15:9: error: ‘sort’ was not declared in this scope; did you mean ‘short’?
   15 |         sort(A.begin(), A.end());
      |         ^~~~
      |         short
answer.code:46:13: error: ‘st’ was not declared in this scope; did you mean ‘std’?
   46 |             st.insert(x.front());
      |             ^~
      |             std
answer.code:49:12: error: ‘next_permutation’ was not declared in this scope
   49 |     }while(next_permutation(A.begin(), A.end()));
      |            ^~~~~~~~~~~~~~~~
answer.code:51:11: error: ‘st’ was not declared in this scope; did you mean ‘std’?
   51 |     cout<<st.size()<<endl;
      |           ^~
      |           std