#include <bits/stdc++.h>
using namespace std;
#if __has_include("Today's/debug.cpp")
#include "Today's/debug.cpp"
#else
#define debug(...)
#define print_line
#define debugc(...)
#define cerr \
	if (false) cerr
#endif

int main() {
	int n, m;
	cin >> n >> m;
	vector<long long> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a.begin(), a.end());
	long long ans = 0;
	for (int i = 0; i < m - 1; i++) {
		ans += (a[i + 1] - a[i]) * (a[i + 1] - a[i]);
	}
	long long tmp = ans;
	for (int i = 1; i + m - 1 < n; i++) {
		tmp -= (a[i] - a[i - 1]) * (a[i] - a[i - 1]);
		tmp += (a[i + m - 1] - a[i + m - 2]) * (a[i + m - 1] - a[i + m - 2]);
		ans = min(ans, tmp);
	}
	cout << ans << endl;
}