#include <bits/stdc++.h>
using namespace std;

const int MAX_N = 300001;
long long N, A, B, W, D[MAX_N], E[MAX_N], zero[MAX_N], one[MAX_N];

int main() {
  int i, j, k, oneLen;
  long long t, oneMin;

  scanf("%lld %lld %lld %lld", &N, &A, &B, &W);

  D[0] = E[0] = 0;
  for (i = 1; i <= N; i++) {
    scanf("%lld", &D[i]);
    E[i] = E[i - 1] - A + i * B;
  }

  zero[0] = one[0] = W;
  zero[1] = zero[0] + D[1];
  one[1] = one[0] + E[1];
  oneLen = 1;
  for (i = 2; i <= N; i++) {
    zero[i] = std::min(zero[i - 1], one[i - 1]) + D[i];

    oneMin = zero[i - 1] + E[1];
    k = 1;
    for (j = 2; j <= oneLen + 1; j++) {
      t = zero[i - j] + E[j];
      if (t <= oneMin) {
        oneMin = t;
        k = j;
      }
    }
    one[i] = oneMin;
    oneLen = k;
  }

  printf("%lld\n", std::min(zero[N], one[N]));
  return 0;
}