Language: C++

#include <bits/stdc++.h> 
using namespace std;
unordered_map<int,int> m;
int main() {
  int n,k;
  cin >> n >> k;
  while(k--) {
	int d;
    cin >> d;
    while(d--) {
      int t;
      cin >> t;
      m.insert(t);
    }
  }
  cout << n - (int)m.size() << "\n";
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:13:15: error: no matching function for call to 'std::unordered_map<int, int>::insert(int&)'
   13 |       m.insert(t);
      |       ~~~~~~~~^~~
In file included from /usr/include/c++/14/unordered_map:41,
                 from /usr/include/c++/14/functional:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/unordered_map.h:571:9: note: candidate: 'template<class _Pair> std::__enable_if_t<((bool)std::is_constructible<typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::value_type, _Pair&&>::value), std::pair<typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::iterator, bool> > std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(_Pair&&) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >]'
  571 |         insert(_Pair&& __x)
      |         ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:571:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/bits/stl_pair.h:60,
                 from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/type_traits: In substitution of 'template<bool _Cond, class _Tp> using std::__enable_if_t = typename std::enable_if::type [with bool _Cond = false; _Tp = std::pair<std::__detail::_Node_iterator<std::pair<const int, int>, false, false>, bool>]':
/usr/include/c++/14/bits/unordered_map.h:571:2:   required by substitution of 'template<class _Pair> std::__enable_if_t<((bool)std::is_constructible<std::pair<const int, int>, _Pair&&>::value), std::pair<std::__detail::_Node_iterator<std::pair<const int, int>, false, false>, bool> > std::unordered_map<int, int>::insert(_Pair&&) [with _Pair = int&]'
a.cc:13:15:   required from here
   13 |       m.insert(t);
      |       ~~~~~~~~^~~
/usr/include/c++/14/type_traits:138:11: error: no type named 'type' in 'struct std::enable_if<false, std::pair<std::__detail::_Node_iterator<std::pair<const int, int>, false, false>, bool> >'
  138 |     using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
      |           ^~~~~~~~~~~~~
/usr/include/c++/14/bits/unordered_map.h:609:9: note: candidate: 'template<class _Pair> std::__enable_if_t<((bool)std::is_constructible<typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::value_type, _Pair&&>::value), typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::iterator> std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(const_iterator, _Pair&&) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >]'
  609 |         insert(const_iterator __hint, _Pair&& __x)
      |         ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:609:9: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/unordered_map.h:624:9: note: candidate: 'template<class _InputIterator> void std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(_InputIterator, _InputIterator) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >]'
  624 |         insert(_InputIterator __first, _InputIterator __last)
      |         ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:624:9: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/unordered_map.h:445:7: note: candidate: 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert_return_type std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(node_type&&) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >; insert_return_type = std::_Hashtable<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::insert_return_type; node_type = std::_Hashtable<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::node_type]'
  445 |       insert(node_type&& __nh)
      |       ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:445:26: note:   no known conversion for argument 1 from 'int' to 'std::unordered_map<int, int>::node_type&&' {aka 'std::_Hashtable<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::node_type&&'}
  445 |       insert(node_type&& __nh)
      |              ~~~~~~~~~~~~^~~~
/usr/include/c++/14/bits/unordered_map.h:450:7: note: candidate: 'std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::iterator std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(const_iterator, node_type&&) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >; iterator = std::__detail::_Insert_base<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::iterator; const_iterator = std::__detail::_Insert_base<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::const_iterator; node_type = std::_Hashtable<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::node_type]'
  450 |       insert(const_iterator, node_type&& __nh)
      |       ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:450:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/unordered_map.h:559:7: note: candidate: 'std::pair<typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::iterator, bool> std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::insert(const value_type&) [with _Key = int; _Tp = int; _Hash = std::hash<int>; _Pred = std::equal_to<int>; _Alloc = std::allocator<std::pair<const int, int> >; typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _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 _Key&> > >::value, false, true> >::iterator = std::__detail::_Insert_base<int, std::pair<const int, int>, std::allocator<std::pair<const int, int> >, std::__detail::_Select1st, std::equal_to<int>, std::hash<int>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::iterator; value_type = std::pair<const int, int>]'
  559 |       insert(const value_type& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/unordered_map.h:559:32: note:   no known conversion for argument 1 from 'int' to 'const std::unordered_map<int, int>::value_type&' {aka 'const std::pair<const int, int>&'}
  559 |       insert(const value_type& __x)
      |              ~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/unordered_map.h:565:7: note: candidate: 'std::pair<typename std::_Hashtable<_Key, std::pair<const _Key, _Val>, _Alloc, std::__detail::_Select1st, _Pred, _Hash, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_poli