#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<string>
#define lol(i,n) for(int i=0;i<n;i++)
#define mod 1000000007
typedef long long ll;
using namespace std;
ll x[60],y[60];
pair<ll,ll> lis[60];
int main(){
	int n,k;
	cin>>n>>k;
	lol(i,n){
		cin>>x[i]>>y[i];
		lis[i]=make_pair(y[i],i);
	}
	sort(lis,lis+n);
	ll ans=(ll)mod*(ll)mod*4;
	for(int i=0;i<n;i++){
		for(int j=i+1;j<n;j++){
			ll left=lis[i].first;
			ll right=lis[j].first;
			vector<ll> v;
			for(int r=0;r<n;r++){
				if(left<=y[r]&&y[r]<=right){
					v.push_back(x[r]);
				}
			}
			sort(v.begin(),v.end());
			for(int r=k-1;r<v.size();r++){
				ans=min(ans,(v[r]-v[r-k+1])*(right-left));
			}
		}
	}
	cout<<ans<<endl;
	return 0;
}
