#include<bits/stdc++.h>
using namespace std;
using Int=long long;
using Real=long double;
template<class T>inline bool chmin(T&A,T B){return(A>B?A=B,1:0);}
template<class T>inline bool chmax(T&A,T B){return(A<B?A=B,1:0);}
#define REP(i,n)for(int i=0;i<(n);++i)
#define REP1(i,n)for(int i=1;i<=(n);++i)
#define ALL(x)begin(x),end(x)
#define drop(x){cout<<x<<'\n';return;}
int N,M,A[1<<17];
void sol()
{
	cin>>N>>M;
	REP(i,N)cin>>A[i];
	sort(A,A+N);
	multiset<Int>st;
	auto f=[&](Int x){return x*x;};
	Int mt=0;
	REP(i,M-1)mt+=f(A[i+1]-A[i]);
	Int ans=mt;
	for(int i=M-1;i<N-1;++i)
	{
		mt+=f(A[i+1]-A[i]);
		mt-=f(A[i-M+2]-A[i-M+1]);
		chmin(ans,mt);
	}
	cout<<ans<<endl;
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	cout<<fixed<<setprecision(16);
	int T=1;
	//cin>>T;
	while(T--)sol();
}