Problem Description

Recently, Cossack Beard found a chess piece and $n$ points lying on the same straight line. The initial coordinate of the chess piece is $x$, and the coordinate of the $i$-th point is $a_i$.

Cossack Beard can first choose any positive integer $k$. After that, he can change the coordinate of the chess piece any number of times by adding or subtracting $k$. That is, he moves the chess piece a distance of $k$ to either side.

Cossack Beard wants to know: what is the maximum possible $k$ such that the chess piece can visit all the given $n$ points.

Input Format

The first line contains two integers $n$ and $x$ ($2 \le n \le 10^5, -10^{18} \le x \le 10^{18}$), which represent the number of points on the line and the initial coordinate of the chess piece, respectively.

The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($-10^{18} \le a_i \le 10^{18}$), which are the coordinates of the points. It is guaranteed that all numbers in the array $a$ are pairwise distinct.

Output Format

Output one number, the maximum value of $k$ such that the chess piece can visit all $n$ given points.

3 2
10 -2 5

1

5 5
1 7 -1 11 15

2

6 0
0 -2019 84 -6 102 87

3

Hint

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