#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <map>
#include <set>
#include <queue>
#include <iomanip>
#include <cstring>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i,n) for (int i = 0; i < int(n);i++)
using mint = modint998244353;

int main(){
  int n,m;
  cin >> n >> m;
  vector<ll> a(n);
  for (int i = 0; i < n;i++){
    cin >> a[i];
  }
  sort(a.begin(),a.end());
  ll ans = 1LL << 60;
  ll res = 0;
  for (int i = 0; i < m-1;i++){
    res += (a[i+1]-a[i])*(a[i+1]-a[i]);
  }
  ans = min(ans,res);
  for (int i = m-1; i < n-1;i++){
    res -= (a[i-m+2]-a[i-m+1])*(a[i-m+2]-a[i-m+1]);
    res += (a[i+1]-a[i])*(a[i+1]-a[i]);
    ans = min(ans,res);
  }
  cout << ans << endl;
  

  return 0;
}