#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define rep1(i, n) for (ll i = 1; i <= (n); ++i)
#define rrep(i, n) for (ll i = n; i > 0; --i)
#define bitrep(i, n) for (ll i = 0; i < (1 << n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define yesNo(b) ((b) ? "Yes" : "No")
using ll = long long;
using ull = unsigned long long;
using ld = long double;
string alphabet = "abcdefghijklmnopqrstuvwxyz";
string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const double pi = 3.141592653589793;
ll smallMOD = 998244353;
ll bigMOD = 1000000007;

int main()
{
    int n, m;
    cin >> n >> m;
    vector<ll> a(n);
    rep(i, n) cin >> a[i];
    sort(all(a));
    ll ans = INT64_MAX;
    rep(i, n - m + 1)
    {
        ll x = 0;
        rep(j, m - 1)
        {
            x += (a[i + j + 1] - a[i + j]) * (a[i + j + 1] - a[i + j]);
        }
        ans = min(ans, x);
    }
    cout << ans << endl;
    return 0;
}