#include <bits/stdc++.h>
using namespace std;

template<class T>
struct ConvexHullTrick {
	vector<pair<T, T>> ls;

	bool need(pair<T, T> l1, pair<T, T> l2, pair<T, T> l3) {
		return -(l2.second - l1.second) * (l3.first - l2.first) < -(l3.second - l2.second) * (l2.first - l1.first);
	}

	void add(T a, T b) {
		pair<T, T> l(a, b);
		while (ls.size() >= 2 && !need(ls[ls.size() - 2], ls[ls.size() - 1], l)) ls.pop_back();
		ls.emplace_back(l);
	}

	T f(int k, T x) {
		return ls[k].first * x + ls[k].second;
	}

	T minimum(T x) {
		int pass = ls.size() - 1, fail = -1;
		while (pass - fail > 1) {
			int mid = (pass + fail) / 2;
			(f(mid, x) <= f(mid + 1, x) ? pass : fail) = mid;
		}
		return f(pass, x);
	}
};

int main() {
	long long N, A, B, W;
	cin >> N >> A >> B >> W;
	vector<long long> D(N);
	for (int i = 0; i < N; i++) scanf("%lld", &D[i]);

	ConvexHullTrick<long long> cht;
	cht.add(0, 0);
	vector<long long> dp(N + 1);

	for (long long i = 0; i < N; i++) {
		dp[i + 1] = cht.minimum(i) + i * (i + 1) / 2 * B - A * i + D[i];
		cht.add(-i * B, i * (i - 1) / 2 * B + A * i + dp[i]);
	}

	long long ans = LLONG_MAX;
	for (long long i = 0; i <= N; i++) {
		long long cand = dp[i] + (N - i) * (N - i + 1) / 2 * B - A * (N - i);
		ans = min(ans, cand);
	}
	cout << W + ans << endl;
}