#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
#include <random>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<int, ll> i_ll;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int N; ll A, B, W;
	cin >> N >> A >> B >> W;
	vector<ll> D(N);
	for (ll& x: D) scanf("%lld", &x);
	N++; D.push_back(0);
	int M = 1;
	vector<i_ll> p; p.push_back(i_ll(0, 0));
	ll ans;
	for (ll i = 0; i < N; i++) {
		ll mi = p[0].second - B * i * p[0].first;
		if (M >= 2) mi = min(mi, p[1].second - B * i * p[1].first);
		ll lb = 0, ub = M - 1;
		while (ub - lb > 1) {
			ll mid = (lb + ub) / 2;
			ll x1 = p[mid].second - B * i * p[mid].first;
			ll x2 = p[mid + 1].second - B * i * p[mid + 1].first;
			if (x1 > x2) lb = mid;
			else ub = mid;
			mi = min(mi, min(x1, x2));
		}
		mi += i*(i+1)/2 * B - i * A + D[i];
		ans = mi;
		i_ll _p(i + 1, mi + i*(i+1)/2 * B + (i+1) * A);
		for (; M >= 2 && (p[M - 1].second - p[M - 2].second) * (_p.first - p[M - 1].first) >= (_p.second - p[M - 1].second) * (p[M - 1].first - p[M - 2].first); M--, p.pop_back());
		M++; p.push_back(_p);
		
	}
	cout << W + ans << endl;
}