#include "bits/stdc++.h"

#include <unordered_set>
#include <unordered_map>

//#include <iostream>//POJ
//#include <vector>
//#include <string>
//#include <iomanip>
//#include <math.h>
//#include <algorithm>
//#include <cstring>
using namespace std;
#define setc cin.tie(0);ios::sync_with_stdio(0)
#define dd(n) cout<<fixed<<setprecision(n)
#define inp(x) (cin>>x,x)
#define ind(x) (cin>>x,--x)
//#define repi(i,a,b) for(int i=(a), i##_len=(b); i<i##_len; ++i)
#define repi(i,a,b) for(int i=(a);i<b;++i)
#define rep(i,n) repi(i,0,n)
#define repi_(i,a,b) for(int i=(a), i##_len=(b); i<=i##_len; ++i)
#define rep_(i,n) repi_(i,0,n)
#define repir(i,a,b) for(int i=(a)-1, i##_first=(b); i>=i##_first; --i)
#define repr(i,n) repir(i,n,0)
#define repir_(i,a,b) for(int i=(a), i##_first=(b); i>=i##_first; --i)
#define repr_(i,n) repir_(i,n,0)
#define prep(i,n) for(int i=0;i*i<n;++i)
#define prepi(i,a,b) for(int i=a;i*i<b;++i)
#define all(x) (x).begin(),(x).end()
#define vsort(v) sort((v).begin(), (v).end())
#define vcsort(v,c) sort((v).begin(),(v).end(),c)
#define vrev(v) reverse((v).begin(), (v).end())
#define fnd(v,x) ((v).find(x)!=string::npos)
#define mod(a,b) (a<0?a%b+abs(b):a%b)
#define cl(a,b) (a+b-1/b)

//template<typename T> T vpop(vector<T> *v) {
//	T d = v->back();
//	v->pop_back();
//	return d;
//}
//char vpop(string *v) {
//	char d = v->back();
//	v->pop_back();
//	return d;
//}
#define siz(v) ((int)(v).size())
#define ers(v, n) (v).erase((v).begin() + n)
#define cnt(v, n) count(all(v), n)
#define vmin(v) *min_element(v.begin(), v.end())
#define vmax(v) *max_element(v.begin(), v.end())
#define contain(q) !q.empty()
#define cont(q) !q.empty()
//#define qpop(q, a, b) a=q.back().first;b=q.back().second;q.pop()
//#define pqpop(p, a, b) a=q.top().first;b=q.top().second;q.pop()
#define el "\n"
#define sp " "
#define pi 3.14159265358979
#define co(x) cout<<x<<el
#define coc(c, a, b) co(((c)?a:b))
#define cim(x) {cin>>x;--x;}
#define cim2(a,b) {cin>>a>>b;--a;--b;}
#define cosp(x) cout<<(x)<<' '
#define YES(c) coc(c,"YES", "NO")
#define Yes(c) coc(c,"Yes", "No")
#define yes(c) coc(c,"yes", "no")
#define POSSIBLE(c) coc(c, "POSSIBLE", "IMPOSSIBLE")
#define Possible(c) coc(c, "Possible", "Impossible")
#define possible(c) coc(c, "possible", "impossible")
#define inf INT_MAX
#define wildcard(T) numeric_limits<T>::min()
#define noway() {co(-1);gc();return 0;}

#define pb push_back
#define pq priority_queue
#define np next_permutation

#ifdef tqktmp_2
#define gc() getchar(); getchar()
#else
#define gc() 1
#endif
const unsigned int bf0 = (1 << 0);
const unsigned int bf1 = (1 << 1);
const unsigned int bf2 = (1 << 2);
const unsigned int bf3 = (1 << 3);
const unsigned int bf4 = (1 << 4);
const unsigned int bf5 = (1 << 5);
const unsigned int bf6 = (1 << 6);
const unsigned int bf7 = (1 << 7);
const int _10j9p7 = 1000000007;

//#define lint long long
typedef long long lint;
typedef vector<int> IV; typedef vector<string> SV;
typedef vector<lint> LIV;
typedef vector<vector<int>> IVV;
typedef pair<int,int> P; typedef pair<lint,lint> LP;
typedef vector<P> PV; typedef vector<LP> LPV;

const int
dx8[8] ={ 0,1,1,1,0,-1,-1,-1 },
dy8[8] ={ 1,1,0,-1,-1,-1,0,1 },
dx9[9] ={ 0,1,1,1,0,0,-1,-1,-1 },
dy9[9] ={ 1,1,0,-1,0,-1,-1,0,1 },
dx5[5] ={ 0,1,0,0,-1 },
dy5[5] ={ 1,0,0,-1,0 },
dx4[4] ={ 0,1,0,-1 },
dy4[4] ={ 1,0,-1,0 };
//template<class... A> void cim_(A... args) {
//	for (A *i : initializer_list<A*>{ args... }) {
//		cin>>*i;--*i;
//	}
//	return;
//}

template<class T>inline bool maxi(T &a,const T &b){ if(a < b){ a = b; return 1; } return 0; }
template<class T>inline bool mini(T &a,const T &b){ if(b < a){ a = b; return 1; } return 0; }

#define MAX_N 1000
const int md = 1e9+7;

//座標圧縮
struct C{
	lint x,y;
};

vector<C> c;//this to
bool table[50][50]={};//this
lint s[51][51]={};
map <lint,lint> yax,xax;//table[yax[y]][xax[x]]とすることでそこにあるかわかる
bool cmp_C_xless(C a,C b){ return a.x<b.x; }
bool cmp_C_yless(C a,C b){ return a.y<b.y; }
P coordsCompress(lint n=siz(c)){//表のサイズを返す
	P ret={ 0,0 };
	vcsort(c,cmp_C_xless);
	lint r=n,prv=-inf;
	lint kaburi=0;
	rep(i,r){
		xax.insert({ c[i].x,i });
		if(prv==c[i].x){
			continue;
		}prv=c[i].x;
		++ret.first;
	}
	vcsort(c,cmp_C_yless);
	r=n;prv=-inf;
	rep(i,r){
		yax.insert({ c[i].y,i });
		if(prv==c[i].y){
			table[i-++kaburi][xax[c[i].x]]=1;
			continue;
		}prv=c[i].y;
		table[i-kaburi][xax[c[i].x]]=1;
		++ret.second;
	}
	return ret;
}

int main(){
	setc;

	lint n,K;cin>>n>>K;
	c.resize(n);
	rep(i,n){
		cin>>c[i].x>>c[i].y;//--c[i].x;--c[i].y;
	}
	P b=coordsCompress(n);
	//rep(j,b.second){//ここら辺はデバッグ用に残しておいて最後に削除したほうがいい
	//	rep(i,b.first){
	//		cout<<(table[j][i]?'#':'.');
	//	}cout<<el;
	//}
	LIV xscales,yscales;
	for(auto i:xax){
		xscales.pb(i.first);
	}
	for(auto j:yax){
		yscales.pb(j.first);
	}
	rep(j,b.second){//2D CSum
		rep(i,b.first){
			s[j+1][i+1]=table[j][i]+s[j][i+1]+s[j+1][i]-s[j][i];
			//cout<<s[j+1][i+1]<<sp;
		}//cout<<el;
	}lint ans=INT64_MAX;
	rep(pl,b.second){
		rep(ql,b.first){
			repi(pr,pl,b.second){
				repi(qr,ql,b.first){
					if(s[pr+1][qr+1]-s[pr+1][ql]-s[pl][qr+1]+s[pl][ql]>=K){
						mini(ans,(xscales[qr]-xscales[ql])*(yscales[pr]-yscales[pl]));
					}
				}
			}
		}
	}co(ans);
	gc();
}

Measured memory_bytes: 256