#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
#define Add(x, y) (x + y >= mod) ? (x + y - mod) : (x + y)
#define lowbit(x) x & (-x)
#define pi pair<ll, ll>
#define pii pair<ll, pair<ll, ll>>
#define iip pair<pair<ll, ll>, ll>
#define ppii pair<pair<ll, ll>, pair<ll, ll>>
#define ls(k) k << 1
#define rs(k) k << 1 | 1
#define fi first
#define se second
#define full(l, r, x) for(auto it = l; it != r; ++it) (*it) = x
#define Full(a) memset(a, 0, sizeof(a))
#define open(s1, s2) freopen(s1, "r", stdin), freopen(s2, "w", stdout);
#define For(i, l, r) for(register int i = l; i <= r; ++i)
#define _For(i, l, r) for(register int i = r; i >= l; --i)
using namespace std;
using namespace __gnu_pbds;
typedef double db;
typedef unsigned long long ull;
typedef long long ll;
bool Begin;
const int N = 1010;
inline ll read(){
    ll x = 0, f = 1;
    char c = getchar();
    while(c < '0' || c > '9'){
        if(c == '-')
          f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9'){
        x = (x << 1) + (x << 3) + (c ^ 48);
        c = getchar();
    }
    return x * f;
}
inline void write(ll x){
	if(x < 0){
		putchar('-');
		x = -x;
	}
	if(x > 9)
	  write(x / 10);
	putchar(x % 10 + '0');
}
ll n, a, b, w;
ll s[N], d[N];
bool End;
int main(){
	n = read(), a = read(), b = read(), w = read();
	s[0] = s[1] = w;
	for(ll i = 2; i <= n + 1; ++i){
		d[i] = read();
		s[i] = s[i - 1] + d[i];
		for(ll j = 1; j < min(i, 1200ll); ++j)
		  s[i] = min(s[i], s[i - j - 1] - j * a + (j * (j + 1) >> 1) * b + d[i - j]);
	}
	write(s[n + 1]);
	cerr << '\n' << abs(&Begin - &End) / 1048576 << "MB";
	return 0;
}