#include <iostream>
#include <deque>
#include <algorithm>

#define rep(i, n) for(int i = 0; i < (n); ++i)

using namespace std;

typedef long long ll;
typedef __int128 lll;

const ll inf = 1e12;

int n, a, b, w;
int d[300000];
ll dp[300001];
deque<int> k;

ll pt(int k){
	return -ll(k) * b;
}
ll ct(int k){
	return dp[k] + ll(k) * a + k * ll(k + 1) / 2 * b;
}
ll f(int k, int x){
	return pt(k) * x + ct(k);
}

bool rm(int p, int q, int r){
	return lll(ct(q) - ct(r)) * (pt(p) - pt(q)) >= lll(ct(p) - ct(q)) * (pt(q) - pt(r));
}

void calc(){
	dp[0] = w;
	for(int i = 1; i <= n; ++i){
		while(k.size() >= 2 && rm(k[k.size() - 2], k.back(), i - 1)){
			k.pop_back();
		}
		k.push_back(i - 1);
		while(k.size() >= 2 && f(k[0], i) >= f(k[1], i)){
			k.pop_front();
		}
		dp[i] = f(k[0], i) + d[i - 1] + i * ll(i - 1) / 2 * b - ll(i - 1) * a;
	}
}

int main(){
	cin >> n >> a >> b >> w;
	rep(i, n){
		cin >> d[i];
	}

	calc();
	
	ll ans = inf;
	rep(i, n + 1){
		ans = min(dp[n - i] + i * ll(i + 1) / 2 * b - ll(i) * a, ans);
	}
	cout << ans << endl;
	return 0;
}