#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
//#include<cctype>
#include<climits>
#include<iostream>
#include<string>
#include<vector>
#include<map>
//#include<list>
#include<queue>
#include<deque>
#include<algorithm>
//#include<numeric>
#include<utility>
//#include<memory>
#include<functional>
#include<cassert>
#include<set>
#include<stack>
#include<random>

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, -1, 0, 1};
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int, int> pii;

const int MAXN = 300300;
ll dp[MAXN];
int deq[MAXN];
int N, A, B, W;

bool check(int f1, int f2, int f3) {
    ll a1 = -(ll)B*f1, b1 = (ll)f1*A + ((ll)f1*f1+f1)/2 * B + dp[f1];
    ll a2 = -(ll)B*f2, b2 = (ll)f2*A + ((ll)f2*f2+f2)/2 * B + dp[f2];
    ll a3 = -(ll)B*f3, b3 = (ll)f3*A + ((ll)f3*f3+f3)/2 * B + dp[f3];
    return (a2-a1) * (b3-b2) >= (b2-b1) * (a3-a2);
}

ll f(int j, int x) {
    return -(ll)B*j*x + (ll)j*A + ((ll)j*j+j)/2*B + dp[j];
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> N >> A >> B >> W;
    vector<int> D(N);
    for (int i = 0; i < N; i++)
        cin >> D[i];
    dp[0] = 0;
    int s = 0, t = 1;
    deq[0] = 0;
    for (int i = 1; i <= N; i++) {
        while (s+1 < t && f(deq[s], i) >= f(deq[s+1], i)) s++;
        dp[i] = f(deq[s], i) + D[i-1] - (ll)(i-1)*A + ((ll)i*i-i)/2*B;
        // 末尾から最小値を取る可能性がなくなったものを取り除く
        while (s+1 < t && check(deq[t-2], deq[t-1], i)) t--;
        deq[t++] = i;
    }
    ll ans = 1ll<<60;
    for (int i = 0; i <= N; i++) {
        ll d = N-i;
        ans = min(ans, dp[i]+B*(d+1)*d/2 - A*d);
    }
    cout << ans+W << endl;
    return 0;
}