#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <tuple>        //tuple
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits
#include <functional>

using namespace std;
constexpr long long int D_MOD = 1000000007;



int main() {

	int N, M;
	cin >> N >> M;

	vector<int64_t> A(N), B(N - 1);
	for (int i = 0; i < N; i++) {
		cin >> A.at(i);
	}

	sort(A.begin(), A.end());
	for (int i = 0; i < N - 1; i++) {
		B.at(i) = (A.at(i + 1) - A.at(i)) * (A.at(i + 1) - A.at(i));
	}

	int64_t ans = 0;
	sort(B.begin(), B.end());
	for (int i = 0; i < M - 1; i++) {
		ans += B.at(i);
	}

	cout << ans << endl;

	return 0;

}