#include "bits/stdc++.h"
#ifndef err
#define err(...)(void)0
#endif
using namespace std;
using ll = long long;
using ull = decltype(1ull);
template<class T>int size(T&&a) { return a.size(); }
#define REP(t,a)for(typename make_signed<decltype(a.second)>::type t=a.first,_l##t=a.second;t<_l##t;t++)
#define RREP(t,a)for(typename make_signed<decltype(a.second)>::type t=a.second-1,_l##t=a.first;t>=_l##t;t--)
template<class B>pair<int, B>make_pair(B b) { return{ 0,b }; }
#define rep(t,...)REP(t,make_pair(__VA_ARGS__))
#define rrep(t,...)RREP(t,make_pair(__VA_ARGS__))
#define all(a)begin(a),end(a)
#define rall(a)a.rbegin(),a.rend()
#define var(t, ...) t __VA_ARGS__;in,__VA_ARGS__;

void Calc();
int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);
  cin.exceptions(istream::failbit | istream::badbit);
  cout << fixed << setprecision(15); Calc(); cout.flush(); return 0;
}
template<class A>void amax(A&a, A b) { a = max(a, b); }
template<class A>void amin(A&a, A b) { a = min(a, b); }
template<class A>int comp(A a, A b) { return a < b ? 1 : b < a ? -1 : 0; }
struct Scanner {
  template<class A = string>A Next() { A a; cin >> a; return a; }
  template<class A = int>vector<A>Array(int n) { vector<A>a(n); for (A&i : a) cin >> i; return a; }
  string Line() const { string s; getline(cin, s); return s; }
  template<class A>Scanner&operator,(A&a) { a = Next<A>(); return *this; }
  template<class A>operator A() { return Next<A>(); }
}in;

/*---------------------------------------------------------------------*/

template<class ...T>tuple<T...>Init(T... t) { return tuple<T...>{ t... }; }
template<class T>tuple<T> Init(T t) { return tuple<T>{ t }; }
template<int N, int...I>struct idx_seq : idx_seq<N - 1, 0, (I + 1)...> {};
template<int...I>struct idx_seq<0, I...> {};
template<class R, class T, int...I>R InitInternal(T&&a, idx_seq<0, I...>) { return R{ get<I>(a)... }; }
template<class T, class B, class...V>struct Vec {
  typedef Vec<T, V...>A; typedef vector<typename A::t>t; t nvec(B a, V...b) { return t(a, A().nvec(b...)); }
};
template<class T, class B>struct Vec<T, B> {
  using X = typename conditional<is_same<T, nullptr_t>::value, int, T>::type;
  typedef vector<X>t; t nvec(B a) { return t(a); }
};
template<class T, class ...C>struct Vec<T, tuple<C...>> {
  template<class A, class B>static pair<A, B> X(A, B);
  template<class...A>static tuple<A...> X(A...);
  using t = typename conditional < is_same<T, nullptr_t>::value, decltype(X(C{}...)), T > ::type;
  t nvec(tuple<C...> a) { return InitInternal<t>(a, idx_seq<sizeof...(C)>()); }
};
template<class T, class C>struct Vec<T, tuple<C>> {
  using X = typename conditional<is_same<T, nullptr_t>::value, C, T>::type;
  using t = X; t nvec(tuple<C> a) { return { get<0>(a) }; }
};
template<class T = nullptr_t, class...B> typename Vec<T, B...>::t nvec(B...b) { return Vec<T, B...>().nvec(b...); }

auto dp = nvec(0, 0, 0);
int n;
const int INF = 1e9 - 1;
vector<int> a;
int z, w;
int dfs(int i, int j, int t) {
  if (i == n - 1) {
    if (j == -1) return abs(a[i] - w);
    return abs(a[i] - a[j]);
  }
  //err(i, j, t);
  auto& ans = dp[i][j + 1][t];
  if (ans != -1) return ans;

  if (t)ans = INF;

  rep(k, i + 1, n) {
    auto c = dfs(k, k - 1, 1 - t);
    if (t)
      amin(ans, c);
    else
      amax(ans, c);
  }
  return ans;
}
void Calc() {

  in, n, z, w;
  err(n, z, w);
  a = in.Array(n);
  dp = nvec(n, n + 10, 2, Init(-1));
  auto ans = dfs(0, -1, 0);
  amax(ans, abs(w - a[n - 1]));
  cout << (ans) << endl;

}


Measured memory_bytes: 220416