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.
from math import gcd
from functools import reduce
def find_gcd(list):
    x = reduce(gcd, list)
    return x

N,D = [int(i) for i in input().split()]
H = [abs(int(i)-D) for i in input().split()]

print(find_gcd(H))
from math import gcd
from functools import reduce
def find_gcd(list):
    x = reduce(gcd, list)
    return x

N,D = [int(i) for i in input().split()]
H = [abs(int(i)-D) for i in input().split()]

print(find_gcd(H))