import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

void chmin(T)(ref T t, in T f) { if (t > f) t = f; }
void chmax(T)(ref T t, in T f) { if (t < f) t = f; }

int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); }


/*
  dp[i] = min{ dp[j] - A (i - j - 1) + B (i - j - 1) (i - j) / 2 + D[i] | 0 <= j < i }
        = min{ (dp[j] + A j + B j (j + 1) / 2) - (B j) i | 0 <= j < i } - A (i - 1) + B i (i - 1) / 2 + D[i]
*/

int N;
long A, B, W;
long[] D;

void main() {
  try {
    for (; ; ) {
      N = readInt();
      A = readLong();
      B = readLong();
      W = readLong();
      D = new long[N + 2];
      foreach (i; 1 .. N + 1) {
        D[i] = readLong();
      }
      
      debug {
        auto dp = new long[N + 2];
        dp[0] = W;
        foreach (i; 1 .. N + 2) {
          dp[i] = iota(0, i).map!(j => (dp[j] + A * j + B * j * (j + 1) / 2) - (B * j) * i).minElement - A * (i - 1) + B * i * (i - 1) / 2 + D[i];
        }
        writeln(dp);
      }
      
      long ans;
      auto q = new Tuple!(long, long)[N + 2];
      int qHead, qTail;
      foreach (i; 0 .. N + 2) {
        long x;
        if (i == 0) {
          x = W;
        } else {
          for (; qTail - qHead >= 2 && q[qHead][0] - q[qHead][1] * i >= q[qHead + 1][0] - q[qHead + 1][1] * i; ++qHead) {}
          x = q[qHead][0] - q[qHead][1] * i - A * (i - 1) + B * i * (i - 1) / 2 + D[i];
        }
        debug {
          writeln(i, " ", x);
        }
        if (i == N + 1) {
          ans = x;
        } else {
          const p = Tuple!(long, long)(x + A * i + B * i * (i + 1) / 2, B * i);
          // ([-1][0] - [-2][0]) / ([-1][1] - [-2][1]) >= (p[0] - [-2][0]) / (p[1] - [-2][1])
          for (; qTail - qHead >= 2 && (q[qTail - 1][0] - q[qTail - 2][0]) * (p[1] - q[qTail - 2][1]) >= (p[0] - q[qTail - 2][0]) * (q[qTail - 1][1] - q[qTail - 2][1]); --qTail) {}
          q[qTail++] = p;
        }
      }
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}