As lockdown is going on so no is allowed to go outside , so Chef has come with an innovative idea for food home delivery using drone.  But there is an issue with it , the drone can move forward or backward a fix number of steps $x$ . 
All the houses and chef restaurant are all in a straight line . Homes which need delivery are located at $H[i]$ and chef is located at $y$ coordinate . 
If Drone is at a location $R$, then it can move to $R-x$ or $R+x$ . 
Help chef find maximum value of $x$ to complete all the deliveries as he is busy managing the orders.

-----Input:-----
- First line will contain $n$ and $R$, number of houses that need delivery and the correct coordinate of chef (Drone).
- Second line contains $n$ integers , the coordinate of all homes that need delivery. 

-----Output:-----
- The maximum value of $x$ , so that drone delivers to all houses.

-----Constraints-----
- $1 \leq n \leq 1000$
- $1 \leq R \leq 10^9$
- $1 \leq hi \leq 10^9$
- $1 \leq x  \leq 10^9$

-----Sample Input:-----
3 1
3 5 11

-----Sample Output:-----
2

-----EXPLANATION:-----
Chef's drone is at 1 initially and he needs to visit 3,5,11 , so optimal solution will be (maximum value of x ) equal to 2.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'from sys import stdin,stdout\r\nimport bisect\r\nfrom collections import defaultdict\r\ndef main():\r\n    #for _ in range(int(stdin.readline())):\r\n    n,d=map(int,stdin.readline().split())\r\n    arr=[int(k) for k in stdin.readline().split()]\r\n    arr.sort()\r\n    ind=bisect.bisect_left(arr,d)\r\n    diff=-1\r\n    if ind!=n and arr[ind]==d:\r\n        if ind==n-1:\r\n            diff=abs(arr[ind-1]-d)\r\n        else:\r\n            diff=min(abs(arr[ind+1]-d),abs(arr[ind-1]-d))\r\n    else:\r\n        if ind==n:\r\n            diff=abs(arr[ind-1]-d)\r\n        else:\r\n            diff=abs(arr[ind]-d)\r\n    counter=0\r\n    for i in range(1,n):\r\n        if abs(arr[i]-arr[i-1])%diff!=0:\r\n               counter=1\r\n               break\r\n    if counter==1:\r\n        print(1)\r\n    else:\r\n        print(diff)\r\n                   \r\n                \r\n        \r\n                \r\n            \r\ndef __starting_point():\r\n    main()\n__starting_point()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 14981