#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
const ll MAX_N = 2e5;

deque<tuple<ll, ll, ll>> deq;
ll N, A, B, W;

void add(ll a, ll b, ll c){
    deq.push_back({a, b, c});
}

ll f(tuple<ll, ll, ll> coef, ll x){
    ll a = get<0>(coef);
    ll b = get<1>(coef);
    ll c = get<2>(coef);
    return (a*x*x + b*x+c)/2;
}

ll query(ll x){
    while(deq.size()>=2){
        tuple<ll, ll, ll> coef0 = deq.front();
        deq.pop_front();
        tuple<ll, ll, ll> coef1 = deq.front();
        deq.pop_front();
        if(f(coef0, x) >= f(coef1, x)){
            deq.push_front(coef1);
        }else{
            deq.push_front(coef1);
            deq.push_front(coef0);
            break;
        }
    }

    return f(deq.front(), x);
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    cin >> N >> A >> B >> W;
    vector<ll> D(N+1);
    for(ll i=1; i<=N; i++) cin >> D[i];

    vector<ll> dp(N+1);
    dp[0] = W;
    add(B, B-2*A, 2*W);
    for(ll i=1; i<=N; i++){
        dp[i] = query(i);
        add(B, B-2*B*i-2*A, B*i*i-B*i+2*A*i+2*dp[i-1]+2*D[i]);
    }

    cout << dp[N] << endl;
}