#include <iostream>
#include <algorithm>
#include <bitset>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <array>
#include <unordered_map>
#include <complex>
#include <deque>
#include <cassert>
#include <cmath>
#include <functional>
#include <iomanip>
#include <chrono>
#include <random>
#include <numeric>
using namespace std;

#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define bit(n) (1LL<<(n))
#define sz(x) ((int)(x).size())
#define TEN(n) ((ll)(1e##n))
#define fst first
#define snd second

string DBG_DLM(int &i){return(i++==0?"":", ");}
#define DBG_B(exp){int i=0;os<<"{";{exp;}os<<"}";return os;}
template<class T>ostream&operator<<(ostream&os,vector<T>v);
template<class T>ostream&operator<<(ostream&os,set<T>v);
template<class T>ostream&operator<<(ostream&os,queue<T>q);
template<class T>ostream&operator<<(ostream&os,priority_queue<T>q);
template<class T,class K>ostream&operator<<(ostream&os,pair<T,K>p);
template<class T,class K>ostream&operator<<(ostream&os,map<T,K>mp);
template<class T,class K>ostream&operator<<(ostream&os,unordered_map<T,K>mp);
template<int I,class TPL>void DBG(ostream&os,TPL t){}
template<int I,class TPL,class H,class...Ts>void DBG(ostream&os,TPL t){os<<(I==0?"":", ")<<get<I>(t);DBG<I+1,TPL,Ts...>(os,t);}
template<class T,class K>void DBG(ostream&os,pair<T,K>p,string delim){os<<"("<<p.first<<delim<<p.second<<")";}
template<class...Ts>ostream&operator<<(ostream&os,tuple<Ts...>t){os<<"(";DBG<0,tuple<Ts...>,Ts...>(os,t);os<<")";return os;}
template<class T,class K>ostream&operator<<(ostream&os,pair<T,K>p){DBG(os,p,", ");return os;}
template<class T>ostream&operator<<(ostream&os,vector<T>v){DBG_B(forr(t,v){os<<DBG_DLM(i)<<t;});}
template<class T>ostream&operator<<(ostream&os,set<T>s){DBG_B(forr(t,s){os<<DBG_DLM(i)<<t;});}
template<class T>ostream&operator<<(ostream&os,queue<T>q){DBG_B(for(;q.size();q.pop()){os<<DBG_DLM(i)<<q.front();});}
template<class T>ostream&operator<<(ostream&os,priority_queue<T>q){DBG_B(for(;q.size();q.pop()){os<<DBG_DLM(i)<<q.top();});}
template<class T,class K>ostream&operator<<(ostream&os,map<T,K>m){DBG_B(forr(p,m){os<<DBG_DLM(i);DBG(os,p,"->");});}
template<class T,class K>ostream&operator<<(ostream&os,unordered_map<T,K>m){DBG_B(forr(p,m){os<<DBG_DLM(i);DBG(os,p,"->");});}
#define DBG_OVERLOAD(_1,_2,_3,_4,_5,_6,macro_name,...)macro_name
#define DBG_LINE(){char s[99];sprintf(s,"line:%3d | ",__LINE__);cerr<<s;}
#define DBG_OUTPUT(v){cerr<<(#v)<<"="<<(v);}
#define DBG1(v,...){DBG_OUTPUT(v);}
#define DBG2(v,...){DBG_OUTPUT(v);cerr<<", ";DBG1(__VA_ARGS__);}
#define DBG3(v,...){DBG_OUTPUT(v);cerr<<", ";DBG2(__VA_ARGS__);}
#define DBG4(v,...){DBG_OUTPUT(v);cerr<<", ";DBG3(__VA_ARGS__);}
#define DBG5(v,...){DBG_OUTPUT(v);cerr<<", ";DBG4(__VA_ARGS__);}
#define DBG6(v,...){DBG_OUTPUT(v);cerr<<", ";DBG5(__VA_ARGS__);}
#define DEBUG0(){DBG_LINE();cerr<<endl;}
#ifdef LOCAL
#define out(...){DBG_LINE();DBG_OVERLOAD(__VA_ARGS__,DBG6,DBG5,DBG4,DBG3,DBG2,DBG1)(__VA_ARGS__);cerr<<endl;}
#else
#define out(...)
#endif

using ll=long long;
using pii=pair<int,int>;using pll=pair<ll,ll>;using pil=pair<int,ll>;using pli=pair<ll,int>;
using vs=vector<string>;using vvs=vector<vs>;using vvvs=vector<vvs>;
using vb=vector<bool>;using vvb=vector<vb>;using vvvb=vector<vvb>;
using vi=vector<int>;using vvi=vector<vi>;using vvvi=vector<vvi>;
using vl=vector<ll>;using vvl=vector<vl>;using vvvl=vector<vvl>;
using vd=vector<double>;using vvd=vector<vd>;using vvvd=vector<vvd>;
using vpii=vector<pii>;using vvpii=vector<vpii>;using vvvpii=vector<vvpii>;
template<class A,class B>bool amax(A&a,const B&b){return b>a?a=b,1:0;}
template<class A,class B>bool amin(A&a,const B&b){return b<a?a=b,1:0;}
ll ri(){ll l;cin>>l;return l;} string rs(){string s;cin>>s;return s;}

template<class T> struct DequeV {
	vector<T> arr;
	size_t head = 0, tail = 0;
	void clear() { head = tail = 0; arr.clear();}
	int size() const { return tail - head; }
	bool empty() const { return tail == head; }
	T front() const { return arr[head]; }
	T back() const { return arr[tail - 1]; }
	T front(int i) const { return arr[head + i]; }
	T back(int i) const { return arr[tail - 1 - i]; }
	void pop_front() { head++; }
	void pop_back() { tail--; }
	void push_back(T v) {
		if (tail < arr.size()) arr[tail++] = v;
		else arr.push_back(v), tail++;
	}
};
template<class T>ostream&operator<<(ostream&os,DequeV<T>q){DBG_B(for(;q.size();q.pop_front()){os<<DBG_DLM(i)<<q.front();});}

template<typename T>
struct ConvecHullTrick {
	DequeV<pair<T, T> > lines;
	bool isMonotonicX;
	function<bool(T l, T r)> comp;

	ConvecHullTrick(bool flagX = false, function<bool(T l, T r)> compFunc = [](T l, T r) {return l >= r; })
		:isMonotonicX(flagX), comp(compFunc)  {
		lines.push_back(make_pair(0, 0));
	};

	bool check(pair<T, T> l1, pair<T, T> l2, pair<T, T> l3) {
		if (l1 < l3) swap(l1, l3);
		return (l3.second - l2.second) * (l2.first - l1.first) >= (l2.second - l1.second) * (l3.first - l2.first);
	}

	void add(T a, T b) {
		pair<T, T> line(a, b);
		while (lines.size() >= 2 && check(lines.back(1), lines.back(), line)) lines.pop_back();
		lines.push_back(line);
	}

	T f(int i, T x) {
		return lines.front(i).first * x + lines.front(i).second;
	}

	T f(pair<T, T> line, T x) {
		return line.first * x + line.second;
	}

	T get(T x) {
		if (isMonotonicX) {
			while (lines.size() >= 2 && comp(f(lines.front(), x), f(lines.front(1), x))) lines.pop_front();
			return f(lines.front(), x);
		}
		else {
			int low = -1, high = lines.size() - 1;
			while (high - low > 1) {
				int mid = (high + low) / 2;
				(comp(f(mid, x), f(mid + 1, x)) ? low : high) = mid;
			}
			return f(high, x);
		}
	}
};

void Main() {
	int n = ri();
	ll a = ri(), b = ri(), w = ri();
	vector<int> D(n);
	rep(i, n) D[i] = ri();

	ConvecHullTrick<ll> cht(true);

	vl dp(n+1, 1e18);
	dp[0] = 0;

	rep(i, 1, n+1) {
		dp[i] = cht.get(i) - a * (i-1) + i * (i-1LL) / 2 * b + D[i-1];
		cht.add(-i*b, dp[i]+i*a+i*(i+1LL)/2*b);
	}
	ll ans = 1e18;
	rep(t, n+1) {
		amin(ans, dp[t] - (n+1-t-1) * a + (n+1-t) * (n+1-t-1LL) / 2 * b);
	}
	cout << w + ans << endl;
}

signed main() {
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	Main();
	return 0;
}