#include <stdint.h>
#include <stdlib.h>

#include <algorithm>
#include <iostream>
#include <numeric>
#include <set>
#include <vector>
using namespace std;
using default_counter_t = int64_t;

// macro
#define let auto const&
#define overload4(a, b, c, d, name, ...) name
#define rep1(n) \
  for (default_counter_t i = 0, end_i = default_counter_t(n); i < end_i; ++i)
#define rep2(i, n)                                                           \
  for (default_counter_t i = 0, end_##i = default_counter_t(n); i < end_##i; \
       ++i)
#define rep3(i, a, b)                                    \
  for (default_counter_t i       = default_counter_t(a), \
                         end_##i = default_counter_t(b); \
       i < end_##i; ++i)
#define rep4(i, a, b, c)                                 \
  for (default_counter_t i       = default_counter_t(a), \
                         end_##i = default_counter_t(b); \
       i < end_##i; i += default_counter_t(c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep1(n) \
  for (default_counter_t i = default_counter_t(n) - 1; i >= 0; --i)
#define rrep2(i, n) \
  for (default_counter_t i = default_counter_t(n) - 1; i >= 0; --i)
#define rrep3(i, a, b)                                         \
  for (default_counter_t i         = default_counter_t(b) - 1, \
                         begin_##i = default_counter_t(a);     \
       i >= begin_##i; --i)
#define rrep4(i, a, b, c)                                          \
  for (default_counter_t                                           \
           i = (default_counter_t(b) - default_counter_t(a) - 1) / \
                   default_counter_t(c) * default_counter_t(c) +   \
               default_counter_t(a),                               \
           begin_##i = default_counter_t(a);                       \
       i >= begin_##i; i -= default_counter_t(c))
#define rrep(...) \
  overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)

#define ALL(f, c, ...)                                           \
  (([&](decltype((c)) cccc) {                                    \
    return (f)(std::begin(cccc), std::end(cccc), ##__VA_ARGS__); \
  })(c))

// function
template <class C>
constexpr C& Sort(C& a) {
  std::sort(std::begin(a), std::end(a));
  return a;
}
template <class C>
constexpr auto& Min(C const& a) {
  return *std::min_element(std::begin(a), std::end(a));
}
template <class C>
constexpr auto& Max(C const& a) {
  return *std::max_element(std::begin(a), std::end(a));
}
template <class C>
constexpr auto Total(C const& c) {
  return std::accumulate(std::begin(c), std::end(c), C(0));
}
template <typename T>
auto CumSum(std::vector<T> const& v) {
  std::vector<T> a(v.size() + 1, T(0));
  for (std::size_t i = 0; i < a.size() - size_t(1); ++i) a[i + 1] = a[i] + v[i];
  return a;
}
template <typename T>
constexpr bool ChMax(T& a, T const& b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
constexpr bool ChMin(T& a, T const& b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

void In(void) { return; }

template <typename First, typename... Rest>
void In(First& first, Rest&... rest) {
  cin >> first;
  In(rest...);
  return;
}

template <class T, typename I>
void VectorIn(vector<T>& v, const I n) {
  v.resize(size_t(n));
  rep(i, v.size()) cin >> v[i];
}

void Out(void) {
  cout << "\n";
  return;
}

template <typename First, typename... Rest>
void Out(First first, Rest... rest) {
  cout << first << " ";
  Out(rest...);
  return;
}

constexpr auto yes(const bool c) { return c ? "yes" : "no"; }
constexpr auto Yes(const bool c) { return c ? "Yes" : "No"; }
constexpr auto YES(const bool c) { return c ? "YES" : "NO"; }

// http://koturn.hatenablog.com/entry/2018/08/01/010000
template <typename T, typename U>
inline std::vector<U> MakeNdVector(T n, U val) noexcept {
  static_assert(std::is_integral<T>::value,
                "[MakeNdVector] The 1st argument must be an integer");
  return std::vector<U>(std::forward<T>(n), std::forward<U>(val));
}

template <typename T, typename... Args>
inline decltype(auto) MakeNdVector(T n, Args&&... args) noexcept {
  static_assert(std::is_integral<T>::value,
                "[MakeNdVector] The 1st argument must be an integer");
  return std::vector<decltype(MakeNdVector(std::forward<Args>(args)...))>(
      std::forward<T>(n), MakeNdVector(std::forward<Args>(args)...));
}

template <typename T, std::size_t N,
          typename std::enable_if<(N > 0), std::nullptr_t>::type = nullptr>
struct NdvectorImpl {
  using type = std::vector<typename NdvectorImpl<T, N - 1>::type>;
};  // struct ndvector_impl

template <typename T>
struct NdvectorImpl<T, 1> {
  using type = std::vector<T>;
};  // struct ndvector_impl

template <typename T, std::size_t N>
using NdVector = typename NdvectorImpl<T, N>::type;

#ifdef USE_STACK_TRACE_LOGGER
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Weverything"
#include <glog/logging.h>
#pragma clang diagnostic pop
#endif  //__clang__
#endif  // USE_STACK_TRACE_LOGGER

template <typename T>
struct CoordinateCompress {
  vector<T> xs;

  CoordinateCompress() = default;
  CoordinateCompress(const vector<int64_t>& vs) { Add(vs); }
  CoordinateCompress(const initializer_list<vector<T>>& vs) {
    for (auto& v : vs) {
      Add(v);
    }
  }

  void Add(const vector<T>& vs) {
    size_t dn = vs.size();
    xs.reserve(xs.size() + dn);

    copy(vs.begin(), vs.end(), back_inserter(xs));
  }

  void Add(const T& x) { xs.emplace_back(x); }

  void Build(void) {
    sort(xs.begin(), xs.end());
    xs.erase(unique(xs.begin(), xs.end()), xs.end());
  }

  vector<int64_t> GetId(const vector<T>& vs) const {
    vector<int64_t> ret;
    ret.reserve(vs.size());
    transform(vs.begin(), vs.end(), back_inserter(ret), [&](const T& x) {
      return lower_bound(xs.begin(), xs.end(), x) - begin(xs);
    });
    return ret;
  }

  int64_t GetId(const T& x) const {
    return lower_bound(xs.begin(), xs.end(), x) - begin(xs);
  }

  const T& operator[](const int64_t k) const { return xs[k]; }
};

signed main(int argc, char* argv[]) {
  (void)argc;
#ifdef USE_STACK_TRACE_LOGGER
  google::InitGoogleLogging(argv[0]);
  google::InstallFailureSignalHandler();
#else
  (void)argv;
#endif  // USE_STACK_TRACE_LOGGER
  int64_t N, K;
  In(N, K);
  vector<int64_t> t(N), d(N);
  rep(i, N) In(t[i], d[i]);
  CoordinateCompress<int64_t> cc(t);
  cc.Build();

  int64_t num_kind = int64_t(cc.xs.size());

  rep(i, N) { t[i] = cc.GetId(t[i]); }

  vector<vector<int64_t>> ds(num_kind);
  rep(i, N) { ds[t[i]].emplace_back(d[i]); }

  for (auto& a : ds) {
    ALL(sort, a, greater<int64_t>());
  }

  using P = pair<int64_t, int64_t>;

  vector<P> fr(num_kind);
  rep(i, num_kind) { fr[i] = P(ds[i][0], i); }

  ALL(sort, fr, greater<P>());

  multiset<P, greater<P>> a, b;
  rep(i, N) { b.insert(P(d[i], t[i])); }

  int64_t ans   = 0;
  int64_t sum_f = 0;
  int64_t sum_r = 0;
  rep(x, 1, min(num_kind, K) + 1) {
    if (x == 1) {
      sum_f += fr[0].first;
      auto it = b.find(fr[0]);
      b.erase(it);
      rep(i, K - x) {
        it = b.begin();
        sum_r += (*it).first;
        a.insert(*it);
        b.erase(it);
      }
    } else {
      if (a.count(fr[x - 1]) > 0) {
        auto it = a.find(fr[x - 1]);
        sum_f += (*it).first;
        sum_r -= (*it).first;
        a.erase(it);
      } else {
        auto it = b.find(fr[x - 1]);
        sum_f += (*it).first;
        b.erase(it);
        it = a.end();
        it--;
        sum_r -= it->first;
        a.erase(it);
      }
    }

    ChMax(ans, sum_f + sum_r + x * x);
  }

  cout << ans << endl;

  return EXIT_SUCCESS;
}


Measured memory_bytes: 15872