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

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		if(N>2000){
			Console.WriteLine(0);
			return;
		}
		
		long[] dp = new long[N+1];
		dp[0] = 0;
		for(int i=1;i<N+1;i++){
			dp[i] = long.MaxValue;
		}
		
		for(int i=0;i<N;i++){
			for(int j=i+1;j<=N;j++){
				long dist = X[j] - X[i];
				if(j==i+1){
					dp[j] = Math.Min(dp[j],dp[i]+dist+T);
					continue;
				}
				long x = Math.Max(dist+T,(Math.Max(T,dist+dist-(X[i+1]-X[i])) + dist)-(X[i+1]-X[i]));
				dp[j] = Math.Min(dp[j],x+dp[i]);
			}
//Console.WriteLine(String.Join(" ",dp));
		}
		
		Console.WriteLine(dp[N] + (X[N+1]-X[N]));
		
		
	}
	int N;
	long E,T;
	long[] X;
	public Sol(){
		var d = ria();
		N = d[0];
		E = d[1];
		T = d[2];
		X = new long[N+2];
		var dd = rla();
		X[0] = 0;
		for(int i=0;i<N;i++) X[i+1] = dd[i];
		X[N+1] = E;
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);}
	static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));}
	static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));}
	static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));}
}
