#include <bits/stdc++.h>
using namespace std;
namespace std {
template <class S, class T>
struct hash<pair<S, T>> {
  size_t operator()(const pair<S, T> &p) const {
    return ((size_t)1e9 + 7) * hash<S>()(p.first) + hash<T>()(p.second);
  }
};
template <class T>
struct hash<vector<T>> {
  size_t operator()(const vector<T> &v) const {
    size_t h = 0;
    for (auto i : v) h = h * ((size_t)1e9 + 7) + hash<T>()(i) + 1;
    return h;
  }
};
}  // namespace std
template <class T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[ ";
  for (int i = 0; i < (int)v.size(); i++)
    os << v[i] << (i == v.size() - 1 ? " ]" : ", ");
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const set<T> &v) {
  os << "{ ";
  for (const auto &i : v) os << i << ", ";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const map<T, U> &v) {
  os << "{";
  for (const auto &i : v) os << " " << i.first << ": " << i.second << ",";
  return os << "}";
}
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
void dbgprint(const string &fmt) { cerr << endl; }
template <class H, class... T>
void dbgprint(const string &fmt, const H &h, const T &...r) {
  cerr << fmt.substr(0, fmt.find(",")) << "= " << h << " ";
  dbgprint(fmt.substr(fmt.find(",") + 1), r...);
}
const int inf = (int)1e9;
const double INF = 1e12, EPS = 1e-9;
const int MX = 100010;
long long dp[MX], dp2[MX];
int s, t, deq[MX];
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int n, T;
  cin >> n;
  vector<int> v(n + 2);
  cin >> v[n + 1] >> T;
  for (int i = 0; i < (int)n; i++) cin >> v[i + 1];
  dp[0] = -2ll * v[1];
  long long min1 = 1e18;
  for (int i = 0, j = 0; i < n; i++) {
    while (2ll * (v[i + 1] - v[j + 1]) > T) {
      min1 = min(min1, dp[j]);
      if (s < t && deq[s] == j) s++;
      j++;
    }
    long long tmp = 3ll * v[i + 1] + min1;
    tmp = min(tmp, v[i + 1] + dp2[deq[s]] + T);
    if (i == n - 1) {
      cout << tmp + v[n + 1] - v[n] << endl;
      return 0;
    }
    dp[i + 1] = tmp - 2ll * v[i + 2] - v[i + 1];
    dp2[i + 1] = tmp - v[i + 1];
    while (s < t && dp2[deq[t - 1]] >= dp2[i + 1]) t--;
    deq[t++] = i + 1;
  }
  return 0;
}
