#include <bits/stdc++.h>

typedef long long LL;

const int N = 3e5 + 7;

int q[N], fr, ba;
int n, a, b, d[N];
LL f[N];

LL X(int x) {
  return 1LL * b * x;
}

LL Y(int x) {
  return f[x] + 1LL * a * x + 1LL * x * (x + 1) / 2 * b;
}

int main() {

  scanf("%d%d%d%lld", &n, &a, &b, &f[0]);
  for(int i = 1; i <= n; ++i)
    scanf("%d", &d[i]);

  if(b == 0) {
    printf("%lld\n", f[0] - 1LL * a * n);
    return 0;
  }

  fr = ba = 1;
  for(int i = 1; i <= n + 1; ++i) {
    while(fr < ba && (Y(q[fr + 1]) - Y(q[fr])) <= i * (X(q[fr + 1]) - X(q[fr])))
      ++fr;
    f[i] = f[q[fr]] + d[i] + 1LL * b * (i - q[fr]) * (i - q[fr] - 1) / 2 + 1LL * a * (q[fr] - i + 1);
    while(fr < ba && (Y(i) - Y(q[ba])) * (X(q[ba]) - X(q[ba - 1])) <=
	  (X(i) - X(q[ba])) * (Y(q[ba]) - Y(q[ba - 1])))
      --ba;
    q[++ba] = i;
  }

  printf("%lld\n", f[n + 1]);
  
  return 0;

}