#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<int(n); ++i)
#define repll(i,m,n) for(ll i=m; i<ll(n); ++i)
// #define rep(i,m,n) for(ll i=m; i<n; ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fir first
#define sec second

template<typename T> bool chmin(T& a, T b){
    if(a > b){a = b; return true;}
    return false;
}
template<typename T> bool chmax(T& a, T b){
    if(a < b){a = b; return true;}
    return false;
}

int main(){
    int N, M;
    cin >> N >> M;
    vector<ll> A(N);
    rep(i, 0, N) cin >> A[i];

    sort(all(A));
    ll ans = 1LL << 60;
    ll tmp = 0LL;
    rep(i, 1, M){
        tmp += (A[i] - A[i-1])*(A[i] - A[i-1]);
    }
    chmin(ans, tmp);

    int r = M-1, l = 0;
    while(r < N){
        l++;
        r++;
        tmp -= (A[l] - A[l-1])*(A[l] - A[l-1]);
        tmp += (A[r] - A[r-1])*(A[r] - A[r-1]);
        chmin(ans, tmp);
    }
    cout << ans << endl;

    return 0;
}