#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

/* macro */

#define rep(i, a, n) for (int i = (int)(a); i < (int)(n); i++)
#define rrep(i, a, n) for (int i = ((int)(n)-1); i >= (int)(a); i--)
#define Rep(i, a, n) for (i64 i = (i64)(a); i < (i64)(n); i++)
#define RRep(i, a, n) for (i64 i = ((i64)(n)-i64(1)); i >= (i64)(a); i--)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()

/* macro end */

/* template */

namespace ebi {

#ifdef LOCAL
#define debug(...)                                                      \
    std::cerr << "LINE: " << __LINE__ << "  [" << #__VA_ARGS__ << "]:", \
        debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() {
    std::cerr << std::endl;
}

template <typename Head, typename... Tail> void debug_out(Head h, Tail... t) {
    std::cerr << " " << h;
    if (sizeof...(t) > 0) std::cerr << " :";
    debug_out(t...);
}

template <typename T1, typename T2>
std::ostream &operator<<(std::ostream &os, const std::pair<T1, T2> &pa) {
    return os << pa.first << " " << pa.second;
}

template <typename T1, typename T2>
std::istream &operator>>(std::istream &os, std::pair<T1, T2> &pa) {
    return os >> pa.first >> pa.second;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &vec) {
    for (std::size_t i = 0; i < vec.size(); i++)
        os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    return os;
}

template <typename T>
std::istream &operator>>(std::istream &os, std::vector<T> &vec) {
    for (T &e : vec) std::cin >> e;
    return os;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::optional<T> &opt) {
    if (opt) {
        os << opt.value();
    } else {
        os << "invalid value";
    }
    return os;
}

using std::size_t;
using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;

template <class T> inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> T pow(T x, i64 n) {
    T res = 1;
    while (n > 0) {
        if (n & 1) res = res * x;
        x = x * x;
        n >>= 1;
    }
    return res;
}

template <class T> struct Edge {
    int to;
    T cost;
    Edge(int _to, T _cost = 1) : to(_to), cost(_cost) {}
};

template <class T> struct Graph : std::vector<std::vector<Edge<T>>> {
    using std::vector<std::vector<Edge<T>>>::vector;
    void add_edge(int u, int v, T w, bool directed = false) {
        (*this)[u].emplace_back(v, w);
        if (directed) return;
        (*this)[v].emplace_back(u, w);
    }
};

struct graph : std::vector<std::vector<int>> {
    using std::vector<std::vector<int>>::vector;
    void add_edge(int u, int v, bool directed = false) {
        (*this)[u].emplace_back(v);
        if (directed) return;
        (*this)[v].emplace_back(u);
    }
};

constexpr i64 LNF = std::numeric_limits<i64>::max() / 4;

constexpr int INF = std::numeric_limits<int>::max() / 2;

const std::vector<int> dy = {1, 0, -1, 0, 1, 1, -1, -1};
const std::vector<int> dx = {0, 1, 0, -1, 1, -1, 1, -1};

}  // namespace ebi

namespace ebi {

template <class T> struct convex_hull_trick {
  private:
    bool check(std::pair<T, T> a, std::pair<T, T> b, std::pair<T, T> c) {
        return (b.first - a.first) * (c.second - b.second) >= (c.first - b.first) * (b.second - a.second);
    }

    T f(std::pair<T, T> a, T x) {
        return a.first * x + a.second;
    }
  public:
    convex_hull_trick() = default;

    void add(T a, T b) {
        while(lines.size() >= 2 && check(*(lines.end() - 2) , lines.back(), {a, b})) {
            lines.pop_back();
        }
        lines.emplace_back(a, b);
    }

    T min(T x) {
        assert(!lines.empty());
        while(lines.size() >= 2 && f(lines[0], x) >= f(lines[1], x)) {
            lines.pop_front();
        }
        return f(lines[0], x);
    }

  private:
    std::deque<std::pair<T, T>> lines;
};

}  // namespace ebi

namespace ebi {

void main_() {
    int n;
    i64 a,b,w;
    std::cin >> n >> a >> b >> w;
    convex_hull_trick<i64> cht;
    cht.add(-2*a - b, 2*w + 2*a);
    auto f = [&](i64 r) -> i64 {
        return -a*r + b*r*(r+1) / 2;
    };
    i64 ans = w + f(n);
    rep(i,1,n+1) {
        i64 d;
        std::cin >> d;
        i64 val = cht.min(i);
        i64 res = b * i * i + 2 * d + val;
        res /= 2;
        cht.add(-2*a - 2*b*i - b, b*i*i+b*i+2*a*(i+1)+2*res);
        chmin(ans, res + f(n - i));
    }
    std::cout << ans << '\n';
}

}  // namespace ebi

int main() {
    std::cout << std::fixed << std::setprecision(15);
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int t = 1;
    // std::cin >> t;
    while (t--) {
        ebi::main_();
    }
    return 0;
}