#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORR(i, a, b) for(int i = (a); i > (b); --i)
#define REP(i, n) for(int i = 0; i < (n); ++i)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOREACH(x, a) for(auto &(x) : (a))
#define VECCIN(x)                                                              \
    for(auto &youso_ : (x)) cin >> youso_
#define bitcnt(x) __builtin_popcount(x)
#define lbit(x) __builtin_ffsll(x)
#define rbit(x) (64 - __builtin_clzll(x))
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()
#define cinfast() cin.tie(0), ios::sync_with_stdio(false)
#define precise(x) cout << fixed << setprecision(x)
#define PERM(c)                                                                \
    sort(All(c));                                                              \
    for(bool cp = true; cp; cp = next_permutation(All(c)))
#define COMB(n, k)                                                             \
    for(ll bit = (1LL << k) - 1; bit < (1LL << n); bit = next_combination(bit))
#define PERM2(n, k)                                                            \
    COMB(n, k) {                                                               \
        vector<int> sel;                                                       \
        for(int bitindex = 0; bitindex < n; bitindex++)                        \
            if(bit >> bitindex & 1) sel.emplace_back(bitindex);                \
        PERM(sel) { Printv(sel); }                                             \
    }
#define MKORDER(n)                                                             \
    vector<int> od(n);                                                         \
    iota(All(od), 0LL);

template <typename T = long long> inline T IN() {
    T x;
    cin >> x;
    return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&... tail) {
    cin >> head;
    CIN(move(tail)...);
}
template <class Head> inline void COUT(Head &&head) { cout << (head) << "\n"; }
template <class Head, class... Tail>
inline void COUT(Head &&head, Tail &&... tail) {
    cout << (head) << " ";
    COUT(forward<Tail>(tail)...);
}

#define CCIN(...)                                                              \
    char __VA_ARGS__;                                                          \
    CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
    double __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
    long long __VA_ARGS__;                                                     \
    CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
    string __VA_ARGS__;                                                        \
    CIN(__VA_ARGS__)
#define Printv(v)                                                              \
    {                                                                          \
        REP(hoge, v.size())                                                    \
        cout << v[hoge] << (hoge == v.size() - 1 ? "" : " ");                  \
        cout << "\n";                                                          \
    }
template <typename T = string> inline void eputs(T s) {
    cout << s << "\n";
    exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
    std::fill((T *)array, (T *)(array + N), val);
}

long long next_combination(long long sub) {
    long long x = sub & -sub, y = sub + x;
    return (((sub & ~y) / x) >> 1) | y;
}
template <class T> inline bool chmax(T &a, const T &b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, const T &b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}

// generic lambdas
template <typename first>
#if defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
[[nodiscard]]
#elif defined(__GNUC__) &&                                                     \
    (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 4)
__attribute__((warn_unused_result))
#endif // defined(__has_cpp_attribute) && __has_cpp_attribute(nodiscard)
    static inline constexpr decltype(auto)
    fix(first &&f) noexcept {
    return [f = std::forward<first>(f)](auto &&... args) {
        return f(f, std::forward<decltype(args)>(args)...);
    };
}

template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<bool> VB;
typedef vector<double> VD;
typedef vector<string> VS;

const int INF = 1e9;
const int MOD = 1e9 + 7;
// const int MOD = 998244353;
const ll LINF = 1e18;
const ll dw[] = {1, 1, 0, -1, -1, -1, 0, 1};
const ll dh[] = {0, 1, 1, 1, 0, -1, -1, -1};
#define PI 3.141592653589793230
#define EPS 1e-7

// monotonic
template <typename T, bool isMin> struct ConvexHullTrick {
    using P = pair<T, T>;
    deque<P> H;
    bool empty() const { return H.empty(); }
    void clear() { H.clear(); }

    inline int sgn(T x) { return x == 0 ? 0 : (x < 0 ? -1 : 1); }

    using D = long double;
    inline bool check(const P &a, const P &b, const P &c) {
        if(b.second == a.second || c.second == b.second)
            return sgn(b.first - a.first) * sgn(c.second - b.second) >=
                   sgn(c.first - b.first) * sgn(b.second - a.second);

        // return (b.first-a.first)*(c.second-b.second) >=
        // (b.second-a.second)*(c.first-b.first);
        return D(b.first - a.first) * sgn(c.second - b.second) /
                   D(abs(b.second - a.second)) >=
               D(c.first - b.first) * sgn(b.second - a.second) /
                   D(abs(c.second - b.second));
    }

    void addLine(T m, T b) {
        if(!isMin) m *= -1, b *= -1;
        P line(m, b);
        if(empty()) {
            H.emplace_front(line);
            return;
        }
        if(H.front().first <= m) {
            if(H.front().first == m) {
                if(H.front().second <= b) return;
                H.pop_front();
            }
            while(H.size() >= 2 && check(line, H.front(), H[1])) H.pop_front();
            H.emplace_front(line);
        } else {
            assert(m <= H.back().first);
            if(H.back().first == m) {
                if(H.back().second <= b) return;
                H.pop_back();
            }
            while(H.size() >= 2 && check(H[H.size() - 2], H.back(), line))
                H.pop_back();
            H.emplace_back(line);
        }
    }

    inline T getY(const P &a, const T &x) { return a.first * x + a.second; }

    T query(T x) {
        assert(!empty());
        int l = -1, r = H.size() - 1;
        while(l + 1 < r) {
            int m = (l + r) >> 1;
            if(getY(H[m], x) >= getY(H[m + 1], x))
                l = m;
            else
                r = m;
        }
        if(isMin) return getY(H[r], x);
        return -getY(H[r], x);
    }

    T queryMonotoneInc(T x) {
        assert(!empty());
        while(H.size() >= 2 && getY(H.front(), x) >= getY(H[1], x))
            H.pop_front();
        if(isMin) return getY(H.front(), x);
        return -getY(H.front(), x);
    }

    T queryMonotoneDec(T x) {
        assert(!empty());
        while(H.size() >= 2 && getY(H.back(), x) >= getY(H[H.size() - 2], x))
            H.pop_back();
        if(isMin) return getY(H.back(), x);
        return -getY(H.back(), x);
    }
};

ll dp[300003];
ll ans[300003];

signed main() {
    LCIN(N, A, B, W);
    VL D(N);
    VECCIN(D);
    ConvexHullTrick<ll, true> cht;
    cht.addLine(0, 2 * W);
    FOR(i, 1, N + 1) {
        dp[i] =
            cht.query(i - 1) + i * (i - 1) * B - 2 * A * (i - 1) + 2 * D[i - 1];
        ans[i] = min(dp[i], cht.query(i) + (i + 1) * i * B - 2 * A * i);
        cht.addLine(-2 * i * B, (i * i - i) * B + 2 * A * i + dp[i]);
    }
    cout << ans[N] / 2 << "\n";
}