#include <bits/stdc++.h>
#define int long long int
#define mod(x) ((x % MOD) + MOD) % MOD
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FORE(i,a,b) for(int i=(a);i<=(b);++i)
#define RFOR(i,a,b) for(int i=(b)-1;i>=(a);--i)
#define RFORE(i,a,b) for(int i=(b);i>=(a);--i)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) (c).begin(),(c).end()
#define RALL(c) (c).rbegin(),(c).rend()
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))
#define SZ(c) (int)((c).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define LB(c,x) (int)(lower_bound(ALL(c),x)-(c).begin())
#define UB(c,x) (int)(upper_bound(ALL(c),x)-(c).begin())
#define COUNT(c,x) (UB(c,x)-LB(c,x))
#define UNIQUE(c) SORT(c); (c).erase(unique(ALL(c)),(c).end());
#define COPY(c1,c2) copy(ALL(c1),(c2).begin())
#define EXIST(s,e) (bool)((s).find(e)!=(s).end())
#define PB push_back
#define MP make_pair
#define DEL(v) decltype(v)().swap(v)
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define NL cerr << endl;
#define chmax(a, b) a=(((a)<(b))?(b):(a))
#define chmin(a, b) a=(((a)>(b))?(b):(a))
#define F first
#define S second
using namespace std;
template<typename T1, typename T2> using P = pair<T1,T2>;
template<typename T> using V = vector<T>;
struct edge { int from, to; int cost; };
bool operator< (const edge &edge1, const edge &edge2) { return edge1.cost < edge2.cost; };
const int INF = LLONG_MAX;
const int MOD = 1e9+7;

template<typename T> ostream& operator << (ostream& s, const V<T>& v) {
   s << "[";
   for (int i = 0; i < v.size(); i++) { s << v[i]; if (i < v.size() - 1) s << " "; }
   s << "]";
   return s;
}
template<typename T1, typename T2> ostream& operator << (ostream& s, const P<T1,T2>& p) {
   s << "(" << p.first << "," << p.second << ")";
   return s;
}
template<typename T> ostream& operator << (ostream& s, const set<T>& st) {
   s << "{";
   for (auto i = st.begin(); i != st.end(); ++i) {
      s << *i;
      if (next(i) != st.end()) s << ", ";
   }
   s << "}";
   return s;
}
template<typename T1, typename T2> ostream& operator << (ostream& s, const map<T1,T2>& m) {
   s << "{";
   for (auto i = m.begin(); i != m.end(); ++i) {
      s << i->first << ":" << i->second;
      if (next(i) != m.end()) s << ", ";
   }
   s << "}";
   return s;
}

template<typename T> class CumulativeSum2D
{
   private:
      vector<vector<T>> s;
   public:
      CumulativeSum2D(const vector<vector<T>>& v) {
         int M = v.size(), N = v[0].size();
         s.resize(M+1, vector<int>(N+1));
         for (int i = 0; i < M; i++) {
            for (int j = 0; j < N; j++) {
               s[i+1][j+1] = s[i+1][j] + v[i][j];
            }
         }
         for (int i = 0; i < M; i++) {
            for (int j = 0; j < N; j++) {
               s[i+1][j+1] += s[i][j+1];
            }
         }
      }
      int sum(int i, int j, int k, int l) {
         return s[k+1][l+1] - s[i][l+1] - s[k+1][j] + s[i][j];
      }
};

signed main()
{
   int N, K; cin >> N >> K;
   V<int> x(N), y(N);
   REP(i, N) {
      cin >> x[i] >> y[i];
   }

   V<int> X(N), Y(N);
   COPY(x, X); COPY(y, Y);
   UNIQUE(X); UNIQUE(Y);
   V<V<int>> cnt(X.size(), V<int>(Y.size()));
   REP(i, N) {
      cnt[LB(X, x[i])][LB(Y, y[i])]++;
   }

   CumulativeSum2D<int> cum(cnt);
   int MIN = INF;
   FOR(i, 0, X.size()) {
      FOR(j, 0, Y.size()) {
         FOR(k, i, X.size()) {
            FOR(l, j, Y.size()) {
               if (cum.sum(i,j,k,l) >= K) {
                  chmin(MIN, (X[k] - X[i]) * (Y[l] - Y[j]));
               }
            }
         }
      }
   }
   cout << MIN << endl;

   return 0;
}


Measured memory_bytes: 256