There are $N$ cities on a number line. The $i$-th city is located at coordinate $x_i$.

Your objective is to visit all these cities at least once.

In order to do so, you will first set a positive integer $D$.

Then, you will depart from coordinate $X$ and perform Move $1$ and Move $2$ below, as many times as you like:

-   Move $1$: travel from coordinate $y$ to coordinate $y + D$.
-   Move $2$: travel from coordinate $y$ to coordinate $y - D$.

Find the maximum value of $D$ that enables you to visit all the cities.

Here, to visit a city is to travel to the coordinate where that city is located.

Input is given from Standard Input in the following format:

```
$N$ $X$
$x_1$ $x_2$ $...$ $x_N$
```

Print the maximum value of $D$ that enables you to visit all the cities.

-   All values in input are integers.
-   $1 \leq N \leq 10^5$
-   $1 \leq X \leq 10^9$
-   $1 \leq x_i \leq 10^9$
-   $x_i$ are all different.
-   $x_1, x_2, ..., x_N \neq X$

2

Setting D=2 enables you to visit all the cities as follows, and this is the maximum value of such D.

• Perform Move 2 to travel to coordinate 1.
• Perform Move 1 to travel to coordinate 3.
• Perform Move 1 to travel to coordinate 5.
• Perform Move 1 to travel to coordinate 7.
• Perform Move 1 to travel to coordinate 9.
• Perform Move 1 to travel to coordinate 11.