#include <bits/stdc++.h>
using namespace std;
const int N = (int)3e5;
long long int mpow(long long int a, long long int b) {
  if (b == 0)
    return 1;
  else if (b % 2 == 0) {
    long long int memo = mpow(a, b / 2);
    return memo * memo % (long long int)(1e9 + 7);
  } else
    return mpow(a, b - 1) * a % (long long int)(1e9 + 7);
}
long long int lpow(long long int a, long long int b) {
  if (b == 0)
    return 1;
  else if (b % 2 == 0) {
    long long int memo = lpow(a, b / 2);
    return memo * memo;
  } else
    return lpow(a, b - 1) * a;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
vector<long long int> kaijo_memo;
long long int kaijo(long long int n) {
  if (kaijo_memo.size() > n) return kaijo_memo[n];
  if (kaijo_memo.size() == 0) kaijo_memo.push_back(1);
  while (kaijo_memo.size() <= n)
    kaijo_memo.push_back(kaijo_memo[kaijo_memo.size() - 1] * kaijo_memo.size() %
                         (long long int)(1e9 + 7));
  return kaijo_memo[n];
}
vector<long long int> gyaku_kaijo_memo;
long long int gyaku_kaijo(long long int n) {
  if (gyaku_kaijo_memo.size() > n) return gyaku_kaijo_memo[n];
  if (gyaku_kaijo_memo.size() == 0) gyaku_kaijo_memo.push_back(1);
  while (gyaku_kaijo_memo.size() <= n)
    gyaku_kaijo_memo.push_back(
        gyaku_kaijo_memo[gyaku_kaijo_memo.size() - 1] *
        mpow(gyaku_kaijo_memo.size(), (long long int)(1e9 + 7) - 2) %
        (long long int)(1e9 + 7));
  return gyaku_kaijo_memo[n];
}
long long int nCr(long long int n, long long int r) {
  if (n == r) return 1;
  if (n < r || r < 0) return 0;
  long long int ret = 1;
  ret *= kaijo(n);
  ret %= (long long int)(1e9 + 7);
  ret *= gyaku_kaijo(r);
  ret %= (long long int)(1e9 + 7);
  ret *= gyaku_kaijo(n - r);
  ret %= (long long int)(1e9 + 7);
  return ret;
}
int main(void) {
  long long int n, e, t;
  cin >> n >> e >> t;
  vector<long long int> X;
  X.push_back(0);
  for (int i = 0; i < (int)(n); i++) {
    long long int x;
    cin >> x;
    X.push_back(x);
  }
  X.push_back(e);
  vector<long long int> dp;
  for (int i = 0; i < (int)(n + 1); i++) {
    dp.push_back((long long int)(112345678901234567));
  }
  dp[0] = 0;
  for (int i = 0; i < (int)(n); i++) {
    int j;
    j = n;
    dp[j] = (((dp[j]) > (dp[i] + X[i + 1] - X[i] +
                         max(2 * (X[j] - X[i + 1]), t) + X[j] - X[i + 1]))
                 ? (dp[i] + X[i + 1] - X[i] + max(2 * (X[j] - X[i + 1]), t) +
                    X[j] - X[i + 1])
                 : (dp[j]));
    j = lower_bound(X.begin(), X.end(), X[i + 1] + t + 0.1) - X.begin();
    if (X[j] == X[i + 1] + t / 2.0) j++;
    if (j <= n)
      dp[j] = (((dp[j]) > (dp[i] + X[i + 1] - X[i] +
                           max(2 * (X[j] - X[i + 1]), t) + X[j] - X[i + 1]))
                   ? (dp[i] + X[i + 1] - X[i] + max(2 * (X[j] - X[i + 1]), t) +
                      X[j] - X[i + 1])
                   : (dp[j]));
    j--;
    if (j <= n)
      dp[j] = (((dp[j]) > (dp[i] + X[i + 1] - X[i] +
                           max(2 * (X[j] - X[i + 1]), t) + X[j] - X[i + 1]))
                   ? (dp[i] + X[i + 1] - X[i] + max(2 * (X[j] - X[i + 1]), t) +
                      X[j] - X[i + 1])
                   : (dp[j]));
  }
  cout << dp[n] + e - X[n] << endl;
  return 0;
}
