#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
const ll MOD1000000007 = 1000000007;
const ll MOD998244353 = 998244353;
const ll MOD[3] = {999727999, 1070777777, 1000000007};
const ll LINF = 1LL << 60LL;
const int IINF = (1 << 30) - 1;


void solve(){
    ll n, m; cin >> n >> m;
    vector<ll> a(n); rep(i, n) cin >> a[i];
    sort(all(a));

    if(m==1){
        cout << 0 << endl;
        return;
    }

    ll ans = LINF;
    ll sum = 0;
    for(ll i=0; i<m-2; i++) sum += (a[i+1]-a[i])*(a[i+1]-a[i]);

    for(ll i=m-1; i<n; i++){
        sum += (a[i]-a[i-1])*(a[i]-a[i-1]);
        ans = min(ans, sum);
        sum -= (a[i-(m-1)+1]-a[i-(m-1)])*(a[i-(m-1)+1]-a[i-(m-1)]);
    }

    cout << ans << endl;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    int T=1;
    //cin >> T;
    while(T--) solve();
}