answer.code: In function ‘int main()’:
answer.code:64:30: error: ‘mask’ was not declared in this scope; did you mean ‘std::filesystem::perms::mask’?
   64 |             if (res == 0 and mask != string(n, '1')) {
      |                              ^~~~
      |                              std::filesystem::perms::mask
In file included from /usr/include/c++/13/filesystem:48,
                 from /usr/include/x86_64-linux-gnu/c++/13/bits/stdc++.h:200,
                 from answer.code:1:
/usr/include/c++/13/bits/fs_fwd.h:158:7: note: ‘std::filesystem::perms::mask’ declared here
  158 |       mask              = 07777,
      |       ^~~~