#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"
#include "bitset"

using namespace std;

//const long long int MOD = 998244353;
const long long int MOD = 1000000007;

long long int N, M, K, H, W, L, R;

class Segment_Tree {
	vector<long long int>v;
	vector<long long int>add;
	vector<long long int>modi;
	vector<int>l;
	vector<int>r;
	int num;
	long long int ret;
	bool is_min;
	void Left(int place) {
		if (place >= v.size() / 2) {
			l[place] = place - v.size() / 2;
			return;
		}
		Left(place * 2);
		Left(place * 2 + 1);
		l[place] = l[place * 2];
		return;
	}
	void Right(int place) {
		if (place >= v.size() / 2) {
			r[place] = place - v.size() / 2;
			return;
		}
		Right(place * 2);
		Right(place * 2 + 1);
		r[place] = r[place * 2 + 1];
		return;
	}
	long long int Update(int place) {
		if (place >= v.size() / 2) {
			return v[place];
		}
		if (is_min) {
			v[place] = min(Update(place * 2), Update(place * 2 + 1));
			return v[place];
		}
		v[place] = max(Update(place * 2), Update(place * 2 + 1));
		return v[place];
	}
	void Modify(int a, int b, long long int num, int place) {
		if (l[place] >= a && r[place] <= b) {
			modi[place] = num;
			v[place] = num;
			add[place] = 0;
			return;
		}
		if (l[place] > b || r[place] < a)return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		add[place * 2] += add[place];
		add[place * 2 + 1] += add[place];
		add[place] = 0;
		Modify(a, b, num, place * 2);
		Modify(a, b, num, place * 2 + 1);
		if (is_min)v[place] = min(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		else v[place] = max(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		return;
	}
	void Add(int a, int b, long long int num, int place) {
		if (l[place] >= a && r[place] <= b) {
			if (modi[place] != LLONG_MAX) {
				if (place * 2 < v.size()) {
					modi[place * 2] = modi[place * 2 + 1] = modi[place];
					v[place * 2] = v[place * 2 + 1] = modi[place];
					add[place * 2] = add[place * 2 + 1] = 0;
				}
				modi[place] = LLONG_MAX;
			}
			add[place] += num;
			return;
		}
		if (l[place] > b || r[place] < a)return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		add[place * 2] += add[place];
		add[place * 2 + 1] += add[place];
		add[place] = 0;
		Add(a, b, num, place * 2);
		Add(a, b, num, place * 2 + 1);
		if (is_min)v[place] = min(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		else v[place] = max(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		return;
	}
	void RMQ(int a, int b, int place) {
		if (l[place] >= a && r[place] <= b) {
			if (modi[place] != LLONG_MAX) {
				if (place * 2 < v.size()) {
					modi[place * 2] = modi[place * 2 + 1] = modi[place];
					v[place * 2] = v[place * 2 + 1] = modi[place];
					add[place * 2] = add[place * 2 + 1] = 0;
				}
				modi[place] = LLONG_MAX;
			}
			if (is_min)ret = min(ret, v[place] + add[place]);
			else ret = max(ret, v[place] + add[place]);
			return;
		}
		if (l[place]>b || r[place]<a) return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		add[place * 2] += add[place];
		add[place * 2 + 1] += add[place];
		add[place] = 0;
		RMQ(a, b, place * 2);
		RMQ(a, b, place * 2 + 1);
		if (is_min)v[place] = min(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		else v[place] = max(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		return;
	}
public:
	Segment_Tree(int n, bool min) {
		n++;
		num = 1;
		while (num < n * 2) {
			num *= 2;
		}
		l.resize(num);
		r.resize(num);
		is_min = min;
		if (min) {
			v.resize(num, MOD*MOD);
		}
		else v.resize(num, -MOD*MOD);
		add.resize(num, 0);
		modi.resize(num, MOD*MOD);
		Left(1);
		Right(1);
	}
	void Insert(int place, long long int num, bool update) {
		place += v.size() / 2;
		v[place] = num;
		if (!update)return;
		place /= 2;
		while (place) {
			if (is_min)v[place] = min(v[place * 2], v[place * 2 + 1]);
			else v[place] = max(v[place * 2], v[place * 2 + 1]);
			place /= 2;
		}
	}
	void Modify(int a, int b, long long int num) {
		Modify(a, b, num, 1);
	}
	void Add(int a, int b, long long int num) {
		Add(a, b, num, 1);
	}
	void Init() {
		Update(1);
	}
	long long int RMQ(int a, int b) {
		if (is_min)ret = LLONG_MAX;
		else ret = LLONG_MIN;
		RMQ(a, b, 1);
		return ret;
	}
};

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> R >> K;
	vector<long long int>v(N + 1);
	for (int i = 1; i <= N;i++)cin >> v[i];
	vector<long long int>dp(N + 1, MOD*MOD);
	dp[0] = 0;
	L = 1;
	Segment_Tree sg(N + 1, true);
	sg.Modify(0, N, 0);
	sg.Add(0, 0, v[1]);
	//cout << sg.RMQ(0, 0) << endl;
	for (int i = 1; i <= N; i++) {
		dp[i] = min(dp[i], dp[i - 1] + v[i] - v[i - 1] + K);
		while ((v[i] - v[L]) * 2 > K)L++;
		//cout << i << " " << L << endl;
		if (L < i) {
			dp[i] = min(dp[i], dp[L - 1] + K + v[i] - v[L - 1]);
		}
		if(L>1)dp[i] = min(dp[i], sg.RMQ(0, L - 2));
		if (i != N) {
			sg.Add(i, i, v[i + 1] - v[i] + dp[i]);
			sg.Add(0, i - 1, (v[i + 1] - v[i]) * 3);
		}
	}
	//for (int i = 1; i <= N; i++) {
	//	cout << dp[i] << endl;
	//}
	cout << dp.back()+R-v.back() << endl;
	return 0;
}


Measured memory_bytes: 9984