#include <iostream>
#include <iomanip>
#include <string>
#include <stack>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <regex>
using namespace std;
using pii  = pair<int,int>;
using ll=long long;
using ld=long double;
#define pb push_back
#define mp make_pair
#define stpr setprecision
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define rep(i,n) for(ll i=0;i<(n);++i)
#define Rep(i,a,b) for(ll i=(a);i<(b);++i)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define rRep(i,a,b) for(int i=a;i>=b;i--)
#define crep(i) for(char i='a';i<='z';++i)
#define psortsecond(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.second<b.second;});
#define ALL(x) (x).begin(),(x).end()
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define endl '\n'
int ctoi(const char c){
  if('0' <= c && c <= '9') return (c-'0');
  return -1;
}
ll gcd(ll a,ll b){return (b == 0 ? a : gcd(b, a%b));}
ll lcm(ll a,ll b){return a*b/gcd(a,b);}
constexpr ll MOD=1000000007;
constexpr ll INF=1000000011;
constexpr ll MOD2=998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS=10e-8;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> istream& operator>>(istream& is,vector<T>& v){for(auto&& x:v)is >> x;return is;}
template<typename T,typename U> istream& operator>>(istream& is, pair<T,U>& p){ is >> p.first; is >> p.second; return is;}
template<typename T,typename U> ostream& operator>>(ostream& os, const pair<T,U>& p){ os << p.first << ' ' << p.second; return os;}
template<class T> ostream& operator<<(ostream& os, vector<T>& v){
    for(auto i=begin(v); i != end(v); ++i){
        if(i !=begin(v)) os << ' ';
        os << *i;
    }
    return os;
}

int main(){
    ll N,Z,W,A[2007],key,T=0,m=0,ma,mi;
    cin >> N >> Z >> W;
    rep(i,N){
        cin >> A[i];
    }
    key=A[N-1];
    while(1){
        if(T==0){
            ma=-1;
            if(m==N-1){
                cout << abs(W-key) << endl;
                return 0;
            }
            rRep(i,N-2,m){
                if(ma<abs(A[i]-key)){
                    ma=abs(A[i]-key);
                    Z=A[i];
                    m=i+1;
                }
                else{
                    ma=abs(W-key);
                    cout << ma << endl;
                    return 0;
                }
            }
            if(ma<=abs(W-key)){
                ma=abs(W-key);
                cout << ma << endl;
                return 0;
            }
            T=1;
        }
        else{
            mi=LINF;
            if(m==N-1){
                cout << abs(Z-key) << endl;
                return 0;
            }
            rRep(i,N-2,m){
                if(mi>abs(A[i]-key)){
                    mi=abs(A[i]-key);
                    W=A[i];
                    m=i+1;
                }
                else{
                    mi=abs(Z-key);
                    cout << mi << endl;
                    return 0;
                }
            }
            if(mi>=abs(Z-key)){
                mi=abs(Z-key);
                cout << mi << endl;
                return 0;
            }
            T=0;
        }
    }
}

Measured memory_bytes: 256