#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define sz(x) (int)(x).size()
typedef long long ll;

int N;
ll A, B, W, INF = LLONG_MAX;

int main(){
    cin >> N >> A >> B >> W;
    vector<ll> D(N + 1), dp(N + 1, INF), a(N + 1), b(N + 1);
    rep(i, N)scanf("%lld", &D[i+1]);
    dp[0] = b[0] = W;

    deque<int> l;
    l.push_back(0);

    for(int i = 1; i <= N; ++i){
        ll a1, a2, a3, b1, b2, b3, n;
        while(sz(l) >= 2){
            a1 = a[l[0]], a2 = a[l[1]];
            b1 = b[l[0]], b2 = b[l[1]];
            if(a1*i + b1 >= a2*i + b2)l.pop_front();
            else break;
        }

        dp[i] = D[i] - A*(i - 1) + B*i*(i - 1) / 2;
        dp[i] += a[l[0]] * i + b[l[0]];

        a3 = a[i] = -B*i;
        b3 = b[i] = B*i*(i + 1) / 2 + dp[i] + A*i;

        while(sz(l) >= 2){
            n = sz(l);
            a1 = a[l[n-2]], a2 = a[l[n-1]];
            b1 = b[l[n-2]], b2 = b[l[n-1]];
            if((a2 - a1)*(b3 - b2) >= (b2 - b1)*(a3 - a2))l.pop_back();
            else break;
        }

        l.push_back(i);
    }

    ll ans = INF;
    for(int i = 0; i <= N; ++i){
        int n = N - i;
        ans = min(ans, dp[i] - A*n + B*n*(n + 1) / 2);
    }
    cout << ans << endl;
}