In file included from /usr/include/c++/11/bits/hashtable.h:35,
                 from /usr/include/c++/11/unordered_map:46,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:117,
                 from answer.code:1:
/usr/include/c++/11/bits/hashtable_policy.h: In instantiation of ‘std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::__hash_code std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::_M_hash_code(const _Key&) const [with _Key = Stat; _Value = Stat; _ExtractKey = std::__detail::_Identity; _Hash = std::hash<Stat>; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; bool __cache_hash_code = true; std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::__hash_code = long unsigned int]’:
/usr/include/c++/11/bits/hashtable.h:2079:41:   required from ‘std::pair<typename std::__detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::iterator, bool> std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::_M_insert(_Arg&&, const _NodeGenerator&, std::true_type) [with _Arg = const Stat&; _NodeGenerator = std::__detail::_AllocNode<std::allocator<std::__detail::_Hash_node<Stat, true> > >; _Key = Stat; _Value = Stat; _Alloc = std::allocator<Stat>; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<Stat>; _Hash = std::hash<Stat>; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>; typename std::__detail::_Insert<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::iterator = std::__detail::_Insert_base<Stat, Stat, std::allocator<Stat>, std::__detail::_Identity, std::equal_to<Stat>, std::hash<Stat>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, true, true> >::iterator; typename _Traits::__constant_iterators = std::__detail::_Hashtable_traits<true, true, true>::__constant_iterators; std::true_type = std::integral_constant<bool, true>]’
/usr/include/c++/11/bits/hashtable_policy.h:843:22:   required from ‘std::__detail::_Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::__ireturn_type std::__detail::_Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::insert(const value_type&) [with _Key = Stat; _Value = Stat; _Alloc = std::allocator<Stat>; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<Stat>; _Hash = std::hash<Stat>; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>; std::__detail::_Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::__ireturn_type = std::pair<std::__detail::_Node_iterator<Stat, true, true>, bool>; std::__detail::_Insert_base<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::value_type = Stat]’
/usr/include/c++/11/bits/unordered_set.h:422:27:   required from ‘std::pair<typename std::_Hashtable<_Value, _Value, _Alloc, std::__detail::_Identity, _Pred, _Hash, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<std::__not_<std::__and_<std::__is_fast_hash<_Hash>, std::__is_nothrow_invocable<const _Hash&, const _Tp&> > >::value, true, true> >::iterator, bool> std::unordered_set<_Value, _Hash, _Pred, _Alloc>::insert(const value_type&) [with _Value = Stat; _Hash = std::hash<Stat>; _Pred = std::equal_to<Stat>; _Alloc = std::allocator<Stat>; typename std::_Hashtable<_Value, _Value, _Alloc, std::__detail::_Identity, _Pred, _Hash, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<std::__not_<std::__and_<std::__is_fast_hash<_Hash>, std::__is_nothrow_invocable<const _Hash&, const _Tp&> > >::value, true, true> >::iterator = std::__detail::_Insert_base<Stat, Stat, std::allocator<Stat>, std::__detail::_Identity, std::equal_to<Stat>, std::hash<Stat>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, true, true> >::iterator; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::value_type = Stat]’
answer.code:63:37:   required from here
/usr/include/c++/11/bits/hashtable_policy.h:1215:23: error: static assertion failed: hash...