#include "bits/stdc++.h"
#include <sys/timeb.h>
#include <fstream>
#include <random>

using namespace std;

#define repr(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repr(i,0,n)
#define reprrev(i,a,b) for(int i=(int)(b)-1;i>=(int)(a);i--)
#define reprev(i,n) reprrev(i,0,n)
#define repi(itr,ds) for(auto itr=ds.begin();itr!=ds.end();itr++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define mp make_pair
#define mt make_tuple
#define INF 1050000000
#define INFR INT_MAX
#define INFL (long long)(4e18)
#define INFLR LLONG_MAX
#define EPS (1e-10)
#define MOD 1000000007
#define PI 3.1415926536
#define RMAX 4294967295

typedef long long ll;
typedef pair<int, int> Pi;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<Pi> vPi;
typedef vector<vector<int> > vvi;
typedef vector<vector<bool> > vvb;
typedef vector<vector<ll> > vvll;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<double> > vvd;
typedef vector<vector<Pi> > vvPi;
typedef priority_queue<int, vector<int>, greater<int> > pqli;
typedef priority_queue<ll, vector<ll>, greater<ll> > pqlll;
typedef priority_queue<Pi, vector<Pi>, greater<Pi> > pqlP;
struct Edge {
	int from, to, cost;
	bool operator<(Edge e) {
		return cost < e.cost;
	}
};
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
template <class T>
using vec = vector<T>;
template<class T>
using pql = priority_queue<T, vector<T>, greater<T>>;
string debug_show(Pi a) {
	return "(" + to_string(a.first) + "," + to_string(a.second) + ")";
}
string YN(bool y) { return (y ? "YES" : "NO"); }
string yn(bool y) { return (y ? "Yes" : "No"); }
string ON(bool y) { return (y ? "OK" : "NG"); }

template<class T>
struct augEdge {
	T from, to;
	int cost;
	bool operator<(augEdge e) { return cost < e.cost; }
	bool operator>(augEdge e) { return cost > e.cost; }
};
template<class T>
using augGraph = vector<augEdge<T>>;

int dir4[4][2] = { {0,-1},{-1,0},{1,0},{0,1} };
int dir8[8][2] = { {-1,-1},{0,-1},{1,-1},{-1,0},{1,0},{-1,1},{0,1},{1,1} };

// [a,b]の乱数
int irand(int a, int b) {
	static mt19937 Rand(static_cast<unsigned int>(time(nullptr)));
	uniform_int_distribution<int> dist(a, b);
	return dist(Rand);
}

// [a,b)の乱数
double drand(int a, int b) {
	static mt19937 Rand(static_cast<unsigned int>(time(nullptr)));
	uniform_real_distribution<double> dist(a, b);
	return dist(Rand);
}

//=======ここまでテンプレート===============================================

int N, X, Y;
vll a;
vvll dp;

ll solve(int now, int player) {
	if (dp[now][player] >= 0) {
		return dp[now][player];
	}

	if (player == 0) {
		// X
		ll ans = 0;
		repr(i, now + 1, N) {
			ans = max(ans, solve(i, 1));
		}
		ans = max(ans, abs((now == 0 ? Y : a[now - 1]) - a[N - 1]));
		return dp[now][player] = ans;
	}
	else {
		// Y
		ll ans = INFLR;
		repr(i, now + 1, N) {
			ans = min(ans, solve(i, 0));
		}
		ans = min(ans, abs(a[now - 1] - a[N - 1]));
		return dp[now][player] = ans;
	}
}

int main(void) {
	cin >> N >> X >> Y;
	a = vll(N);
	rep(i, N) {
		cin >> a[i];
	}
	dp = vvll(N + 1, vll(2, -1));

	cout << solve(0, 0) << endl;

	return 0;
}

Measured memory_bytes: 512