In file included from /usr/include/c++/10/map:60,
from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:81,
from hexagon.cpp:2:
/usr/include/c++/10/bits/stl_tree.h: In instantiation of 'static const _Key& std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_S_key(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Const_Link_type) [with _Key = long long int; _Val = long long int; _KeyOfValue = std::_Identity<long long int>; _Compare = cmp_t; _Alloc = std::allocator<long long int>; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Const_Link_type = const std::_Rb_tree_node<long long int>*]':
/usr/include/c++/10/bits/stl_tree.h:1935:36: required from 'std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_lower_bound(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Link_type, std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Base_ptr, const _Key&) [with _Key = long long int; _Val = long long int; _KeyOfValue = std::_Identity<long long int>; _Compare = cmp_t; _Alloc = std::allocator<long long int>; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, cmp_t, std::allocator<long long int> >::iterator; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Link_type = std::_Rb_tree_node<long long int>*; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Base_ptr = std::_Rb_tree_node_base*]'
/usr/include/c++/10/bits/stl_tree.h:1277:30: required from 'std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::lower_bound(const key_type&) [with _Key = long long int; _Val = long long int; _KeyOfValue = std::_Identity<long long int>; _Compare = cmp_t; _Alloc = std::allocator<long long int>; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, cmp_t, std::allocator<long long int> >::iterator; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::key_type = long long int]'
/usr/include/c++/10/bits/stl_set.h:830:32: required from 'std::set<_Key, _Compare, _Alloc>::iterator std::set<_Key, _Compare, _Alloc>::lower_bound(const key_type&) [with _Key = long long int; _Compare = cmp_t; _Alloc = std::allocator<long long int>; std::set<_Key, _Compare, _Alloc>::iterator = std::_Rb_tree<long long int, long long int, std::_Identity<long long int>, cmp_t, std::allocator<long long int> >::const_iterator; std::set<_Key, _Compare, _Alloc>::key_type = long long int]'
hexagon.cpp:45:33: required from here
/usr/include/c++/10/bits/stl_tree.h:780:8: error: static assertion failed: comparison object must be invocable as const
780 | is_invocable_v<const _Compare&, const _Key&, const _Key&>,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~