#include <bits/stdc++.h>

template <typename T>
std::vector<T> Compress(std::vector<T> v) {
  std::sort(v.begin(), v.end());
  v.erase(std::unique(v.begin(), v.end()), v.end());
  return v;
}

template <typename T>
T Uncompress(const std::vector<T>& v, T x) {
  return std::lower_bound(v.begin(), v.end(), x) - v.begin();
}

template <typename T>
std::function<T(T)> Uncompressor(const std::vector<T>& v) {
  return [&v](T i) -> T { return Uncompress(v, i); };
}

template <typename T, typename = void>
struct is_iterable : std::false_type {};
template <typename T>
struct is_iterable<T, std::void_t<decltype(std::begin(std::declval<T>())),
                                  decltype(std::end(std::declval<T>()))>>
    : std::true_type {};

template <typename T, typename = void>
struct is_pair : std::false_type {};
template <typename T>
struct is_pair<T, std::void_t<decltype(std::declval<T>().first),
                              decltype(std::declval<T>().second)>>
    : std::true_type {};

template <typename T>
void debug(const T& v) {
  if constexpr (is_pair<T>::value) {
    std::cerr << "{";
    debug(v.first);
    std::cerr << ", ";
    debug(v.second);
    std::cerr << "}";
  } else if constexpr (is_iterable<T>::value &&
                       !std::is_same<T, std::string>::value) {
    std::cerr << "{";
    for (auto it = v.begin(); it != v.end(); ++it) {
      if (it != v.begin()) std::cerr << ", ";
      debug(*it);
    }
    std::cerr << "}";
  } else {
    std::cerr << v;
  }
}
template <typename T, typename... Ts>
void debug(const T& value, const Ts&... args) {
  debug(value);
  std::cerr << ", ";
  debug(args...);
}
#if DEBUG
#define dbg(...)                        \
  do {                                  \
    cerr << #__VA_ARGS__ << ": ";       \
    debug(__VA_ARGS__);                 \
    cerr << " (L" << __LINE__ << ")\n"; \
  } while (0)
#else
#define dbg(...)
#endif

void read_from_cin() {}
template <typename T, typename... Ts>
void read_from_cin(T& value, Ts&... args) {
  std::cin >> value;
  read_from_cin(args...);
}
#define rd(type, ...) \
  type __VA_ARGS__;   \
  read_from_cin(__VA_ARGS__);
#define ints(...) rd(int, __VA_ARGS__);
#define strings(...) rd(string, __VA_ARGS__);

template <typename T>
void write_to_cout(const T& value) {
  if constexpr (std::is_same<T, bool>::value) {
    std::cout << (value ? "Yes" : "No");
  } else {
    std::cout << value;
  }
}
template <typename T, typename... Ts>
void write_to_cout(const T& value, const Ts&... args) {
  write_to_cout(value);
  std::cout << ' ';
  write_to_cout(args...);
}
#define wt(...)                 \
  do {                          \
    write_to_cout(__VA_ARGS__); \
    cout << '\n';               \
  } while (0)

#define all(x) (x).begin(), (x).end()

#define rep_dispatch(_1, _2, _3, name, ...) name
#define rep3(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rep2(i, n) rep3(i, 0, n)
#define rep1(n) rep2(_loop_variable_, n)
#define rep(...) rep_dispatch(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; --i)

template <typename T>
std::istream& operator>>(std::istream& is, std::vector<T>& v) {
  for (T& vi : v) is >> vi;
  return is;
}

template <typename T, typename U>
bool chmax(T& a, U b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

template <typename T, typename U>
bool chmin(T& a, U b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}

template <typename T>
int sz(const T& v) {
  return v.size();
}

#include <boost/hana/functional/fix.hpp>
const auto& Fix = boost::hana::fix;

using ll = long long;

template <typename T>
using low_priority_queue =
    std::priority_queue<T, std::vector<T>, std::greater<T>>;

template <typename T>
using V = std::vector<T>;
template <typename T>
using VV = V<V<T>>;

using namespace std;

int main() {
#define int ll

  ints(n, K);
  V<int> x(n), y(n);
  rep(i, n) cin >> x[i] >> y[i];

  V<int> cx = Compress(x), cy = Compress(y);
  dbg(cx);
  dbg(cy);

  VV<bool> p(n, V<bool>(n));
  rep(i, n) p[Uncompress(cx, x[i])][Uncompress(cy, y[i])] = true;
  rep(i, n) dbg(p[i]);

  VV<int> dp(n + 1, V<int>(n + 1));
  rep(i, n) rep(j, n) {
    dp[i + 1][j + 1] = dp[i][j + 1] + dp[i + 1][j] - dp[i][j] + p[i][j];
  }
  rep(i, n + 1) dbg(dp[i]);

  int ans = numeric_limits<int>::max();
  // n = 2
  // sz(cx) = 2
  // * * *
  // * * *
  // * * *
  rep(i, n) rep(j, n) rep(k, i + 1, n + 1) rep(l, j + 1, n + 1) {
    if (dp[k][l] - dp[i][l] - dp[k][j] + dp[i][j] >= K) {
      dbg(i, j, k, l);
      dbg(cx[k - 1], cx[i], cy[l - 1], cy[j]);
      chmin(ans, (cx[k - 1] - cx[i]) * (cy[l - 1] - cy[j]));
      dbg(ans);
    }
  }
  wt(ans);
}


Measured memory_bytes: 3640