#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 = 3e5 + 10; 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], T[N]; bool End; int main(){ n = read(), a = read(), b = read(), w = read(); s[0] = s[1] = w; T[0] = s[0] + a; for(ll i = 2; i <= n + 1; ++i){ d[i] = read(); s[i] = 1e18; for(ll l = 0; l < i - 1; ++l) s[i] = min(s[i], T[l] - i * l * b); s[i] += (i * (i - 1) >> 1) * b - i * a; s[i] = min(s[i], s[i - 1] + d[i]); T[i - 1] = s[i - 1] + d[i] + i * a + (i * (i - 1) >> 1) * b; } write(s[n + 1]); cerr << '\n' << abs(&Begin - &End) / 1048576 << "MB"; return 0; }