#include <bits/stdc++.h>
#define whlie while
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define rep(i,N) for(int i = 0; i < (N); i++)
#define repr(i,N) for(int i = (N) - 1; i >= 0; i--)
#define rep1(i,N) for(int i = 1; i <= (N) ; i++)
#define repr1(i,N) for(int i = (N) ; i > 0 ; i--)
#define each(x,v) for(auto& x : v)
#define all(v) (v).begin(),(v).end()
#define sz(v) ((int)(v).size())
#define vrep(v,it) for(auto it = v.begin(); it != v.end(); it++)
#define vrepr(v,it) for(auto it = v.rbegin(); it != v.rend(); it++)
#define ini(...) int __VA_ARGS__; in(__VA_ARGS__)
#define inl(...) ll __VA_ARGS__; in(__VA_ARGS__)
#define ins(...) string __VA_ARGS__; in(__VA_ARGS__)
using namespace std; void solve();
using ll = long long; using vl = vector<ll>;
using vi = vector<int>; using vvi = vector< vector<int> >;
constexpr int inf = 1001001001;
constexpr ll infLL = (1LL << 61) - 1;
struct IoSetupNya {IoSetupNya() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); cerr << fixed << setprecision(7);} } iosetupnya;
template<typename T, typename U> inline bool amin(T &x, U y) { return (y < x) ? (x = y, true) : false; }
template<typename T, typename U> inline bool amax(T &x, U y) { return (x < y) ? (x = y, true) : false; }
template<typename T, typename U> ostream& operator <<(ostream& os, const pair<T, U> &p) { os << p.first << " " << p.second; return os; }
template<typename T, typename U> istream& operator >>(istream& is, pair<T, U> &p) { is >> p.first >> p.second; return is; }
template<typename T> ostream& operator <<(ostream& os, const vector<T> &v) { int s = (int)v.size(); rep(i,s) os << (i ? " " : "") << v[i]; return os; }
template<typename T> istream& operator >>(istream& is, vector<T> &v) { for(auto &x : v) is >> x; return is; }
void in(){} template <typename T,class... U> void in(T &t,U &...u){ cin >> t; in(u...);}
void out(){cout << "\n";} template <typename T,class... U> void out(const T &t,const U &...u){ cout << t; if(sizeof...(u)) cout << " "; out(u...);}
template<typename T>void die(T x){out(x); exit(0);}
#ifdef NyaanDebug
  #include "NyaanDebug.h"
  #define trc(...) do { cerr << #__VA_ARGS__ << " = "; dbg_out(__VA_ARGS__);} while(0)
  #define trca(v,N) do { cerr << #v << " = "; array_out(v , N);} while(0)
#else
  #define trc(...)
  #define trca(...)
  int main(){solve();}
#endif

using P = pair<ll,ll>;
using vp = vector<P>;
constexpr int MOD = /**/ 1000000007; //*/ 998244353;
/////////////////

template<class T>
struct compress{
  vector<T> xs;
  compress(const vector<T>& v){
    xs.reserve(v.size());
    for(T x : v) xs.push_back(x);
    sort(xs.begin(),xs.end());
    xs.erase(unique(xs.begin(),xs.end()) , xs.end());
  }

  int get(const T& x){
    return lower_bound(xs.begin(),xs.end(),x) - xs.begin();
  }
  int size(){
    return xs.size();
  }
  T& operator[](int i){
    return xs[i];
  }
};

template<typename T>
struct BIT2D{
  int H,W;
  vector<vector<T>> bit;
  BIT2D(int H,int W):H(H),W(W){
    bit.resize(H + 1 , vector<T>(W + 1 , 0));
  }
  // (a,b)にwを足す
  void add(int x,int y,T w){
    for(int a = (++y , ++x); a <= H; a += a & -a){
      for(int b = y ; b <= W; b += b & -b){
        bit[a][b] += w;
      }
    }
  }
  //  [(0,0) , (a,b)]の和　閉区間に注意！
  T sum(int x, int y){
    if(x < 0 || y < 0) return 0;
    if(x >= H) x = H - 1;
    if(y >= W) y = W - 1;
    T ret = 0;
    for(int a = (++y , ++x) ; a > 0; a -= a & -a){
      for(int b = y; b > 0; b -= b & -b){
        ret += bit[a][b];
      }
    }
    return ret;
  }

  // [(x1,y1) , (x2,y2)] の和 x1>x2の時はswap
  T sum(int x1,int y1, int x2, int y2){
    if(x1 > x2) swap(x1 , x2);
    if(y1 > y2) swap(y1 , y2);
    return sum(x2,y2)-sum(x2,y1-1)-sum(x1-1,y2)+sum(x1-1,y1-1);
  }
};

void solve(){
  ini(N , K);
  vp v(N); in(v);
  sort(all(v));
  ll ans = 5e18;
  vl x(N) , y(N);
  rep(i , N) x[i] = v[i].fi , y[i] = v[i].se;
  compress<ll> zipx(x) , zipy(y);
  BIT2D<ll> bit(N + 1 , N + 1);
  rep(i , N) {
    trc(i , v[i].fi,v[i].se,zipx.get(v[i].fi) , zipy.get(v[i].se));
    bit.add(zipx.get(v[i].fi) , zipy.get(v[i].se) , 1);
  }
  rep(u,N) rep(d,N) rep(l,N) rep(r,N){
    if(u > d || l > r) continue;
    if(bit.sum(u,l,d,r) >= K) amin(ans , 
      (zipx[d] - zipx[u]) * (zipy[r] - zipy[l])
    );
  }
  out(ans);
}

Measured memory_bytes: 384