#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(int i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{
    long long start_, end_, step_;
   public:
    struct range_iterator{
      long long val, step_;
      range_iterator(long long v, long long step) : val(v), step_(step) {}
      long long operator * (){return val;}
      void operator ++ (){val += step_;}
      bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;}
    };
    range(long long len) : start_(0), end_(len), step_(1) {}
    range(long long start, long long end) : start_(start), end_(end), step_(1) {}
    range(long long start, long long end, long long step) : start_(start), end_(end), step_(step) {}
    range_iterator begin(){ return range_iterator(start_, step_); }
    range_iterator   end(){ return range_iterator(  end_, step_); }
  };

  string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){
    stringstream ss; for(int i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str();
  }

  string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }

}

constexpr long long mod = 9_ten + 7;

int main(){
  long long n,a,b,w;
  cin >> n,a,b,w;

  vector<long long> d(n);
  cin >> d;

  vector<long long> acc(n+1, 0);
  for(auto i : range(n+1) ){
    acc[i] = -(i)*a + (i)*(i+1)/2 * b; //acc[i] -a + (i+1)*b;
  }

  vector<long long> dp(n+1, 1ll<<50);
  dp[0] = 0;

  deque<pair<long long,long long>> L;
  auto get_v = [&](long long x) -> long long{
    if(L.size()==0) return 0;
    long long lb = 0;
    long long ub = L.size();
    while(ub-lb>1){
      long long mid = (lb+ub)/2;
      bool ok = [&](){
        long long v1 = L[mid-1].first * x + L[mid-1].second;
        long long v2 = L[mid  ].first * x + L[mid  ].second;
        return v1>v2;
      }();
      (ok? lb : ub) = mid;
    }
    while(lb){
      L.pop_front();
      lb--;
    }
    return L[0].first * x + L[0].second;
  };

  auto check = [](pair<long long,long long> a, pair<long long,long long> b, pair<long long,long long> c){
    long long a21 = b.first - a.first;
    long long a23 = b.first - c.first;
    long long b32 = c.second - b.second;
    long long b12 = a.second - b.second;
    return a21*b32 >= a23*b12;
  };

  auto add_l = [&](pair<long long, long long> l){
    while(L.size() >= 2 && check(L[L.size()-2], L[L.size()-1], l)){
      L.pop_back();
    }
    L.push_back(l);
  };

  add_l({ -(2*0+1)*b -2*a, 2*dp[0] + 2*a*(0+1) + 0*(0+1)*b });
  for(auto i : range(1, n+1) ){
    dp[i] = 2*d[i-1] + i*i*b + get_v(i);
    pair<long long,long long> nx = { -(2*i+1)*b -2*a, dp[i] + 2*a*(i+1) + i*(i+1)*b };
    add_l(nx);
  }

  long long ans = 1ll<<50;
  for(auto i : range(n+1) ){
    ans = min(ans, dp[i]/2 + acc[n-i] + w);
  }
  println(ans);

  return 0;
}

/*
                                                                                
                                   ### #                                        
                              ############# #                                   
                          #######################                               
                     ################################                           
                 #########################################                      
              ##############################################                    
             #     #####################################     #                  
            ######     ############################     ######                  
            ###########     ###################   # ##########                  
            ################    #########      ###############                  
            ####################        # ####################                  
            #######   ##############  ########################                  
            ########       #########  ########################                  
            ###########      #######  ########################                  
            ############## # #######  ########################                  
            ########################  ########################                  
            ########################  ########################                  
            ########################  ########################                  
              ######################  #######################                   
                 ###################  ###################                       
                      ##############  ###############                           
                          ##########  ##########                                
                              ######  ######                                    
                                  ##  ##                                        
                                                                                
                                                                                
                                                                                
                        #                             #                         
                        #      #                      #                         
        #    #  #    #  #   #      ####   ####     ####   ####   ####           
         #   #  #    #  # ##   #  #      #    #  #    #  #____#  ##             
          # #/  #    #  ## #   #  #      #    #  #    #  #^^^^   #              
           ##    ###/#  #   #  #   ####   ####    ###/#   ####   #              
           #                                                                    
         ##                                                                     
                                                                                
*/