//tail=0 head=0 while(tail>head)
//tail=-1 head=0 while(tail>=head)
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 5e4 + 5;
int n, L, sum[N], q[N], tail, head;
int f[N];

int A(int i) {
	return sum[i] + i;
}

int B(int i) {
	return sum[i] + i + L + 1;
}

int X(int i) {
	return B(i);
}

int Y(int i) {
	return f[i] + B(i) * B(i);
}

double k(int i, int j) {
	return double(Y(j) - Y(i)) / double(X(j) - X(i));
}

signed main() {
	cin >> n >> L;
	for (int i = 1; i <= n; i++) {
		cin >> sum[i];
		sum[i] += sum[i - 1];
	}
	for (int i = 1; i <= n; i++) {
		while (tail > head && 2 * A(i) > k(q[head], q[head + 1]))
			head++;
		int j = q[head];
		f[i] = f[j] + (A(i) - B(j)) * (A(i) - B(j));
		while (tail > head && k(i, q[tail - 1]) < k(q[tail], q[tail - 1]))
			--tail;
		q[++tail] = i;
	}
	cout << f[n] << endl;
	return 0;
}