#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n, m;
    cin >> n >> m;
    vector<ll> a(n);
    rep(i,n) cin >> a[i];
    vector<ll> sum(n+1), ab(n+1);
    sort(a.begin(),a.end());
    rep(i,n) sum[i+1] = sum[i] + a[i]*a[i];
    rep(i,n) ab[i+1] = ab[i] + a[i+1] * a[i];
    ll ans = 5e18;
    dbg(sum, ab);
    rep(i,n){
        int j = i + m -1;
        if(j>=n) break;
        ll tmp = sum[j] - sum[i+1];
        tmp *= 2;
        tmp += a[i]*a[i];
        tmp += a[j]*a[j];
        tmp -= 2 * (ab[j]-ab[i]);
        ans = min(ans, tmp);
    }
    cout << ans << endl;
    return 0;
}