Language: C++

#include <bits/stdc++.h>
using namespace std;
#define repl(i, l, r) for (ll i = (l); i < (r); i++)
#define rep(i, n) repl(i, 0, n)
#define CST(x) cout << fixed << setprecision(x)
using ll = long long;
const ll MOD = 1000000007;
const int inf = 1e9 + 10;
const ll INF = 4e18 + 10;
const int dx[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
const int dy[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0};
int main() {
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(false);

	ll n, k;
	cin >> n >> k;
	pair<ll, ll> p[n];
	rep(i, n) cin >> p[i].second >> p[i].first;
	sort(p, p + n, greater<ll>());
	ll now = 0;
	set<ll> s;
	priority_queue<ll, vector<ll>, greater<ll>> que;
	rep(i, k) {
		now += p[i].first;
		if (s.count(p[i].second)) que.push(p[i].first);
		s.insert(p[i].second);
	}
	ll S = s.size();
	now += S * S;
	priority_queue<ll> Que;
	repl(i, k, n) {
		if (s.count(p[i].second) == 0) {
			Que.push(p[i].first);
			s.insert(p[i].second);
		}
	}
	ll ans = now;
	while (true) {
		if (Que.empty() or que.empty()) break;
		now += Que.top() - que.top();
		Que.pop(), que.pop();
		now += (S + 1) * (S + 1) - S * S;
		S++;
		ans = max(ans, now);
	}
	cout << ans << endl;

	return 0;
}

Compiler output:
In file included from /usr/include/c++/14/bits/stl_algobase.h:71,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'constexpr bool __gnu_cxx::__ops::_Iter_comp_iter<_Compare>::operator()(_Iterator1, _Iterator2) [with _Iterator1 = std::pair<long long int, long long int>*; _Iterator2 = std::pair<long long int, long long int>*; _Compare = std::greater<long long int>]':
/usr/include/c++/14/bits/stl_algo.h:1777:14:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1777 |           if (__comp(__i, __first))
      |               ~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4805:18:   required from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = pair<long long int, long long int>*; _Compare = greater<long long int>]'
 4805 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:21:6:   required from here
   21 |         sort(p, p + n, greater<ll>());
      |         ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:158:30: error: no match for call to '(std::greater<long long int>) (std::pair<long long int, long long int>&, std::pair<long long int, long long int>&)'
  158 |         { return bool(_M_comp(*__it1, *__it2)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:49,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/stl_function.h:394:7: note: candidate: 'constexpr bool std::greater<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = long long int]'
  394 |       operator()(const _Tp& __x, const _Tp& __y) const
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_function.h:394:29: note:   no known conversion for argument 1 from 'std::pair<long long int, long long int>' to 'const long long int&'
  394 |       operator()(const _Tp& __x, const _Tp& __y) const
      |                  ~~~~~~~~~~~^~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Val_comp_iter<_Compare>::operator()(_Value&, _Iterator) [with _Value = std::pair<long long int, long long int>; _Iterator = std::pair<long long int, long long int>*; _Compare = std::greater<long long int>]':
/usr/include/c++/14/bits/stl_algo.h:1757:20:   required from 'void std::__unguarded_linear_insert(_RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Val_comp_iter<greater<long long int> >]'
 1757 |       while (__comp(__val, __next))
      |              ~~~~~~^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1785:36:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1785 |             std::__unguarded_linear_insert(__i,
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
 1786 |                                 __gnu_cxx::__ops::__val_comp_iter(__comp));
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4805:18:   required from 'void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = pair<long long int, long long int>*; _Compare = greater<long long int>]'
 4805 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:21:6:   required from here
   21 |         sort(p, p + n, greater<ll>());
      |         ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:240:30: error: no match for call to '(std::greater<long long int>) (std::pair<long long int, long long int>&, std::pair<long long int, long long int>&)'
  240 |         { return bool(_M_comp(__val, *__it)); }
      |                       ~~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_function.h:394:7: note: candidate: 'constexpr bool std::greater<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = long long int]'
  394 |       operator()(const _Tp& __x, const _Tp& __y) const
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_function.h:394:29: note:   no known conversion for argument 1 from 'std::pair<long long int, long long int>' to 'const long long int&'
  394 |       operator()(const _Tp& __x, const _Tp& __y) const
      |                  ~~~~~~~~~~~^~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Iter_comp_val<_Compare>::operator()(_Iterator, _Value&) [with _Iterator = std::pair<long long int, long long int>*; _Value = std::pair<long long int, long long int>; _Compare = std::greater<long long int>]':
/usr/include/c++/14/bits/stl_heap.h:140:48:   required from 'void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = pair<long long int, long long int>*; _Distance = long int; _Tp = pair<long long int, long long int>; _Compare = __gnu_cxx::__ops::_Iter_comp_val<greater<long long int> >]'
  140 |       while (__holeIndex > __topIndex && __comp(__first + __parent, __value))
      |                                          ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:247:23:   required from 'void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Distance = long int; _Tp = pair<long long int, long long int>; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
  247 |       std::__push_heap(__first, __holeIndex, __topIndex,
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  248 |                        _GLIBCXX_MOVE(__value), __cmp);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:356:22:   required from 'void std::__make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare&) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
  356 |           std::__adjust_heap(__first, __parent, __len, _GLIBCXX_MOVE(__value),
      |           ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  357 |                              __comp);
      |                              ~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1593:23:   required from 'void std::__heap_select(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1593 |       std::__make_heap(__first, __middle, __comp);
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1868:25:   required from 'void std::__partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1868 |       std::__heap_select(__first, __middle, __last, __comp);
      |       ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1884:27:   required from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Size = long int; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<greater<long long int> >]'
 1884 |               std::__partial_sort(__first, __last, __last, __comp);
      |               ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1905:25:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = pair<long long int, long long int>*; _Compare = __gnu_cxx::__ops::_Iter_comp_i