Problem:
Score : 300 points

Problem Statement

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.

Constraints

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

Input

Input is given from Standard Input in the following format:

N X
x_1 x_2 ... x_N

Output

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

Sample Input 1

3 3
1 7 11

Sample Output 1

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.

Sample Input 2

3 81
33 105 57

Sample Output 2

24

Sample Input 3

1 1
1000000000

Sample Output 3

999999999

Solution in Go (1.6) (judge verdict: Runtime Error)

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func NextSlice(n int) []int {
	in := bufio.NewScanner(os.Stdin)
	var mat []int
	in.Scan()
	temp := strings.Split(in.Text(), " ")

	for i := 0; i < n; i++ {
		li, _ := strconv.Atoi(temp[i])
		mat = append(mat, li)
	}
	return mat
}
func main() {
	var n, x int
	fmt.Scan(&n, &x)
	xx := NextSlice(n)

	for i := 0; i < n; i++ {
		if x-xx[i] < 0 {
			xx[i] -= x
		} else {
			xx[i] = x - xx[i]
		}
	}
	sort.Ints(xx)
	for i := 0; i < len(xx); i++ {
		for j := 0; j < len(xx); {
			if xx[j]%xx[i] == 0 {
				j++
			}
			if j == len(xx)-1 {
				fmt.Println(xx[i])
				return
			}
		}
	}
}