Como usar unordered_set que tem elementos vetoriais do par <int, int>

Eu queria ter algo parecido

 unordered_set<vector<pair<int,int>>> us;

mas mesmo sem par:

#include <vector>
#include <unordered_set>
using namespace std;

int main() {
    unordered_set<vector<int>> um;
}

Falha:

In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h: In instantiation of ‘struct std::__detail::_Hash_code_base<std::vector<int>, std::vector<int>, std::__detail::_Identity, std::hash<std::vector<int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>’:
/usr/include/c++/4.8/bits/hashtable_policy.h:1402:10:   required from ‘struct std::__detail::_Hashtable_base<std::vector<int>, std::vector<int>, std::__detail::_Identity, std::equal_to<std::vector<int> >, std::hash<std::vector<int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Hashtable_traits<true, true, true> >’
/usr/include/c++/4.8/bits/hashtable.h:174:11:   required from ‘class std::_Hashtable<std::vector<int>, std::vector<int>, std::allocator<std::vector<int> >, std::__detail::_Identity, std::equal_to<std::vector<int> >, std::hash<std::vector<int> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, true, true> >’
/usr/include/c++/4.8/bits/unordered_set.h:96:18:   required from ‘class std::unordered_set<std::vector<int> >’
prog.cpp:7:32:   required from here
/usr/include/c++/4.8/bits/hashtable_policy.h:1070:12: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
            ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^
In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h:1070:12: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
     struct _Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2,
            ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^
In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h:1082:53: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
                                                     ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^
In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h:1082:53: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
       using __ebo_h1 = _Hashtable_ebo_helper<1, _H1>;
                                                     ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^
prog.cpp: In constructor ‘std::unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type, const hasher&, const key_equal&, const allocator_type&) [with _Value = std::vector<int>; _Hash = std::hash<std::vector<int> >; _Pred = std::equal_to<std::vector<int> >; _Alloc = std::allocator<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type = unsigned int; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::hasher = std::hash<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::key_equal = std::equal_to<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::allocator_type = std::allocator<std::vector<int> >]’:
prog.cpp:7:32: error: invalid use of incomplete type ‘std::unordered_set<std::vector<int> >::hasher {aka struct std::hash<std::vector<int> >}’
     unordered_set<vector<int>> um;
                                ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘std::unordered_set<std::vector<int> >::hasher {aka struct std::hash<std::vector<int> >}’
     struct hash;
            ^
prog.cpp:7:32: note:   when instantiating default argument for call to std::unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type, const hasher&, const key_equal&, const allocator_type&) [with _Value = std::vector<int>; _Hash = std::hash<std::vector<int> >; _Pred = std::equal_to<std::vector<int> >; _Alloc = std::allocator<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type = unsigned int; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::hasher = std::hash<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::key_equal = std::equal_to<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::allocator_type = std::allocator<std::vector<int> >]
     unordered_set<vector<int>> um;
                                ^
In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h: In instantiation of ‘std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _H1, _H2, std::__detail::_Default_ranged_hash, true>::_Hash_code_base(const _ExtractKey&, const _H1&, const _H2&, const std::__detail::_Default_ranged_hash&) [with _Key = std::vector<int>; _Value = std::vector<int>; _ExtractKey = std::__detail::_Identity; _H1 = std::hash<std::vector<int> >; _H2 = std::__detail::_Mod_range_hashing]’:
/usr/include/c++/4.8/bits/hashtable_policy.h:1463:65:   required from ‘std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _H1, _H2, _Hash, _Traits>::_Hashtable_base(const _ExtractKey&, const _H1&, const _H2&, const _Hash&, const _Equal&) [with _Key = std::vector<int>; _Value = std::vector<int>; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::vector<int> >; _H1 = std::hash<std::vector<int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, true, true>]’
/usr/include/c++/4.8/bits/hashtable.h:828:24:   required from ‘std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable(std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::size_type, const _H1&, const _H2&, const _Hash&, const _Equal&, const _ExtractKey&, const allocator_type&) [with _Key = std::vector<int>; _Value = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::vector<int> >; _H1 = std::hash<std::vector<int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>; std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::size_type = unsigned int; std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::allocator_type = std::allocator<std::vector<int> >]’
/usr/include/c++/4.8/bits/hashtable.h:397:26:   required from ‘std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::_Hashtable(std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::size_type, const _H1&, const key_equal&, const allocator_type&) [with _Key = std::vector<int>; _Value = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::vector<int> >; _H1 = std::hash<std::vector<int> >; _H2 = std::__detail::_Mod_range_hashing; _Hash = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>; std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::size_type = unsigned int; std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::key_equal = std::equal_to<std::vector<int> >; std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _H1, _H2, _Hash, _RehashPolicy, _Traits>::allocator_type = std::allocator<std::vector<int> >]’
/usr/include/c++/4.8/bits/unordered_set.h:136:35:   required from ‘std::unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set(std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type, const hasher&, const key_equal&, const allocator_type&) [with _Value = std::vector<int>; _Hash = std::hash<std::vector<int> >; _Pred = std::equal_to<std::vector<int> >; _Alloc = std::allocator<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::size_type = unsigned int; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::hasher = std::hash<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::key_equal = std::equal_to<std::vector<int> >; std::unordered_set<_Value, _Hash, _Pred, _Alloc>::allocator_type = std::allocator<std::vector<int> >]’
prog.cpp:7:32:   required from here
/usr/include/c++/4.8/bits/hashtable_policy.h:1099:63: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
                                                               ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^
In file included from /usr/include/c++/4.8/bits/hashtable.h:35:0,
                 from /usr/include/c++/4.8/unordered_set:47,
                 from prog.cpp:2:
/usr/include/c++/4.8/bits/hashtable_policy.h:1099:63: error: invalid use of incomplete type ‘struct std::hash<std::vector<int> >’
       : __ebo_extract_key(__ex), __ebo_h1(__h1), __ebo_h2(__h2) { }
                                                               ^
In file included from /usr/include/c++/4.8/bits/stl_bvector.h:1134:0,
                 from /usr/include/c++/4.8/vector:65,
                 from prog.cpp:1:
/usr/include/c++/4.8/bits/functional_hash.h:58:12: error: declaration of ‘struct std::hash<std::vector<int> >’
     struct hash;
            ^

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