#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 each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

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

int main(){
    cin >> N >> A >> B >> W;
    
    if(B == 0){
        cout << W - N*A << endl;
        return 0;
    }
    
    vll D(N), cur(1100, INF), nex(1100, INF);
    rep(i, N)scanf("%lld", &D[i]);
    cur[0] = W;
    
    rep(i, N){
        fill(all(nex), INF);
        rep(j, 1100)if(cur[j] != INF){
            if(j != 1100 - 1)
                smin(nex[j+1], cur[j] - A + B*(j+1));
            smin(nex[0], cur[j] + D[i]);
        }
        swap(cur, nex);
    }
    cout << *min_element(all(cur)) << endl;
}