#include <bits/stdc++.h>
using namespace std;
const double PI = acos(0) * 2;
const double EPS = 1e-8;
const long long MOD = 1e9 + 7;
const int MAXN = 1e5 + 5;
const int oo = 1e9;
const double foo = 1e30;
template <class T>
int getbit(T s, int i) {
  return (s >> i) & 1;
}
template <class T>
T onbit(T s, int i) {
  return s | (T(1) << i);
}
template <class T>
T offbit(T s, int i) {
  return s & (~(T(1) << i));
}
template <class T>
int cntbit(T s) {
  return __builtin_popcounll(s);
}
template <class T>
T sqr(T x) {
  return x * x;
}
inline void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
inline void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
int N, E;
long long a[MAXN], dp[MAXN], T;
set<pair<int, int> > s[2];
int main() {
  scanf("%d%d%d", &N, &E, &T);
  for (int i = 0; i < N; i++) scanf("%d", &a[i]);
  for (int i = 0; i < N; i++) dp[i] = oo;
  int cur = 0;
  for (int i = 0; i < N; i++) {
    while (cur <= i && (a[i] - a[cur]) * 2 >= T) {
      int now = T - (cur != 0 ? a[cur - 1] : 0) + (cur != 0 ? dp[cur - 1] : 0);
      int nxt = -2 * a[cur] - (cur != 0 ? a[cur - 1] : 0) +
                (cur != 0 ? dp[cur - 1] : 0);
      if (s[0].find(make_pair(now, cur)) != s[0].end()) {
        s[0].erase(make_pair(now, cur));
        s[1].insert(make_pair(nxt, cur));
      }
      cur++;
    }
    dp[i] = a[i] - (i != 0 ? a[i - 1] : 0) + (i != 0 ? dp[i - 1] : 0) + T;
    if (!s[0].empty()) {
      int now = s[0].begin()->first;
      dp[i] = min(dp[i], a[i] + now);
    }
    if (!s[1].empty()) {
      int now = s[1].begin()->first;
      dp[i] = min(dp[i], 3 * a[i] + now);
    }
    int nxt = T - (i != 0 ? a[i - 1] : 0) + (i != 0 ? dp[i - 1] : 0);
    s[0].insert(make_pair(nxt, i));
  }
  cout << E - a[N - 1] + dp[N - 1];
}
