import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.StringReader;
import java.util.StringTokenizer;

public class Main  implements Runnable {
	long M = 1000000007;
	long[] fac = new long[300001];
	long[] ifac = new long[300001];
    public static void main(String[] args) {

        new Thread(null, new Main(), "", 16 * 1024 * 1024).start();

    }

    public void run() {
    	FastScanner sc = new FastScanner(System.in);
		//long n = Long.parseLong(sc.next());
    	//int[] ar = new int[3];
    	//ar[0]=Integer.parseInt(sc.next());
    	//ar[1]=Integer.parseInt(sc.next());
    	//ar[2]=Integer.parseInt(sc.next());
    	//Arrays.parallelSort(ar);
		int n = Integer.parseInt(sc.next());
		int z = Integer.parseInt(sc.next());
		int w = Integer.parseInt(sc.next());
		//long r = Long.parseLong(sc.next());
		//int l = Integer.parseInt(sc.next());
		//long a = Long.parseLong(sc.next());
		//String s = sc.next();
		//int k = Integer.parseInt(sc.next());
		//int m = Integer.parseInt(sc.next());
		//int x2000 = Integer.parseInt(sc.next());
		//int t = Integer.parseInt(sc.next());
		//int k = 0;
		//int k = Integer.parseInt(sc.next());
		//String str = sc.next();
		//char c[] = str.toCharArray();
		//char a[][] = new char[n];
		//int atmp[] = new int[h];
		//int max= 0;
		//int blackar[][] = new int[h*w][2];
		//int p=0;
		//ArrayList<Integer> lists = new ArrayList<Integer>();
		//lists = new ArrayList;
		PrintWriter out = new PrintWriter(System.out);
		int[] a = new int[n];
		for(int i =0; i < n; i++)
		{
			a[i] = Integer.parseInt(sc.next());
		}
		int ans1=0;
		int ans0 = 0;
		ans0 = Math.abs(a[n-1]-w);
		if(n!=1)
		{
			ans1 = Math.abs(a[n-2]-a[n-1]);
		}
		else
		{
			ans1 = Math.abs(a[n-1]-w);
		}
		out.println(Math.max(ans0, ans1));
		out.flush();
	}

    long mpow(long x, long n){
        long ans = 1;
        while(n != 0){
            if(n%2==1) ans = ans*x % M;
            x = x*x % M;
            n = n >> 1;
        }
        return ans;
    }

    long comb(long a, long b){ //aCbをmod計算
        if(a == 0 && b == 0)return 1;
        if(a < b || a < 0)return 0;
        long tmp = ifac[(int)(a-b)]* ifac[(int)b] % M;
        return tmp * fac[(int)a] % M;
    }
    static class FastScanner {
        private BufferedReader reader = null;
        private StringTokenizer tokenizer = null;
        public FastScanner(String in) {
        	StringReader sr = new StringReader(in);
            reader = new BufferedReader(new BufferedReader(sr));
            tokenizer = null;
        }
        public FastScanner(InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        public String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }

            return tokenizer.nextToken("\n");
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public long nextInt() {
            return Integer.parseInt(next());
        }

    }


}


Measured memory_bytes: 27988