Problem:
Score : 500 points

Problem Statement

We have a deck consisting of N cards. Each card has an integer written on it. The integer on the i-th card from the top is a_i.

Two people X and Y will play a game using this deck. Initially, X has a card with Z written on it in his hand, and Y has a card with W written on it in his hand. Then, starting from X, they will alternately perform the following action:

Draw some number of cards from the top of the deck. Then, discard the card in his hand and keep the last drawn card instead. Here, at least one card must be drawn.

The game ends when there is no more card in the deck. The score of the game is the absolute difference of the integers written on the cards in the two players' hand.

X will play the game so that the score will be maximized, and Y will play the game so that the score will be minimized. What will be the score of the game?

Constraints

All input values are integers.

1 \leq N \leq 2000

1 \leq Z, W, a_i \leq 10^9

Input

Input is given from Standard Input in the following format:

N Z W
a_1 a_2 ... a_N

Output

Print the score.

Sample Input 1

3 100 100
10 1000 100

Sample Output 1

900

If X draws two cards first, Y will draw the last card, and the score will be |1000 - 100| = 900.

Sample Input 2

3 100 1000
10 100 100

Sample Output 2

900

If X draws all the cards first, the score will be |1000 - 100| = 900.

Sample Input 3

5 1 1
1 1 1 1 1

Sample Output 3

0

Sample Input 4

1 1 1
1000000000

Sample Output 4

999999999

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;


#define f(i,a,b) for(int i=(int)(a);i<=(int)(b);i++)
#define char_f(i,a) for(int i=(int)(a);(char)s[i]!='\0';i++)
#define rf(i,a,b) for(int i=(int)(a);i>=(int)(b);i--)
#define llf(i,a,b) for(long long int i=(long long int)(a);i<=(long long int)(b);i++)
#define llrf(i,a,b) for(long long int i=(long long int)(a);i>=(long long int)(b);i--)



#define ll long long
#define fi first
#define se second
#define pb push_back
#define pop pop_back
#define mem(ara) memset((ara),0,sizeof(ara))
#define memn(ara) memset((ara),-1,sizeof(ara))
#define bb begin()
#define ee end()
#define em emplace
#define eb emplace_back





#define si set<int>
#define sd set<double>
#define sll set<long long int>
#define ss set<string>
#define sc set<char>

#define pii pair<int,int>
#define pli pair<long long int,int>
#define pil pair<int,long long int>
#define pll pair<long long int,long long int>
#define pci pair<char,int>
#define pic pair<int,char>
#define pcl pair<char,long long int>
#define plc pair<long long int,char>

#define pss pair<string,string>
#define pcc pair<char,char>

#define pis pair<int,string>
#define psi pair<string,int>
#define pls pair<long long int,string>
#define psl pair<string,long long int>
#define pdd pair<double,double>
#define pcs pair<char,string>
#define psc pair<string,char>



#define vi  vector<int>
#define vll vector<long long int>
#define vd vector<double>
#define vs vector<string>
#define vc vector<char>
#define vii vector<pii>



#define mod 1000000007
#define mx (1<<30)-1
#define llmx (1ll<<62)
#define n_size 100005
#define g_size 10000005
double PI=acos(-1);



///unsigned int uMAX=4294967295;
///unsigned ll int ullMAX=18446744073709551615;





int arr[g_size];



int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

	int n,m,T,res;

	int maxi=-mx,mini=mx,count=0,maxii=-mx;

	int i,j,k;

	bool flag;

	string s1,s2;

	char s[100000];

	int ara[n_size],ara2[n_size];


	cin>>n>>m>>k;

	vi v;

	f(i,0,n-1){
        cin>>res;
        v.pb(res);
	}

    cout<<max(abs(v[n-1]-k),abs(v[n-2]-v[n-1]))<<endl;
}