using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;

using Pair = System.Collections.Generic.KeyValuePair<int, int>;

class Program
{
	public Program() { }

	static void Main(string[] args)
	{
		new Program().prog();
	}
	Scanner cin;
	const int MOD = 1000000007;
	const int INF = int.MaxValue - 10;
	const long INFL = long.MaxValue - 10;
	const double EPS = 1e-7;
	const double PI = 3.1415926536;

	int N;
	void prog()
	{
		cin = new Scanner();
		int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
		int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };

		int N = cin.nextInt();
		int E = cin.nextInt();
		int T = cin.nextInt();
		int[] x = new int[N];
		for (int i = 0; i < N; i++)
		{
			x[i] = cin.nextInt();
		}
		long ans = E;
		int left = 0, right = 0;
		while (true)
		{
			if(right == N - 1)
			{
				ans += Math.Max(2 * (x[right] - x[left]), T);
				break;
			}
			if(x[right + 1] - x[left] <= T)
			{
				if (right != N - 2 && x[right + 2] - x[right + 1] < x[right + 1] - x[right] && x[right + 2] - x[right] > T)
				{
					ans += Math.Max(2 * (x[right] - x[left]), T);
					left = right + 1;
					right = left;
					continue;
				}
				right++;
				continue;
			}
			else
			{
				ans += Math.Max(2 * (x[right] - x[left]), T);
				left = right + 1;
				right = left;
			}
		}
		Console.WriteLine(ans);
	}
}

class Scanner
{
	string[] s;
	int i;

	char[] cs = new char[] { ' ' };

	public Scanner()
	{
		s = new string[0];
		i = 0;
	}

	public string next()
	{
		if (i < s.Length) return s[i++];
		string st = Console.ReadLine();
		while (st == "") st = Console.ReadLine();
		s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
		i = 0;
		return next();
	}

	public int nextInt()
	{
		return int.Parse(next());
	}

	public long nextLong()
	{
		return long.Parse(next());
	}

	public double nextDouble()
	{
		return double.Parse(next());
	}
}