/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>
#include<bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n"
using namespace std;
using ll=long long;
using ld=long double;
using vi = vector<int>;
using vii = vector<vector<int>>;
using vl = vector<ll>;
using vll = vector<vector<ll>>;
using vlll = vector<vector<vector<ll>>>;
using vc = vector<char>;
using vcc = vector<vector<char>>;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
void bl(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void bl2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) {
            for (auto vvv : vv) cout << vvv << " ";
            cout << endl;
        }
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_MATH_HPP
#define DEFINE_MATH_HPP

namespace math {

    using ll = long long;
    ll mod = ll(1e9) + 7;

    class Math {
    public:
        Math() {}
        ll keta(ll num);
        ll gcd(ll a, ll b);
        ll lcm(ll a, ll b);
        ll powm(ll num1, ll num2);
        bool isPrime(ll n);
    };

    ll Math::gcd(ll a, ll b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    ll Math::lcm(ll a, ll b) {
        return a * (b / gcd(a, b));
    }

    ll Math::keta(ll num) {
        ll k = 0;
        while (num > 0) {
            num /= 10;
            k++;
        }
        return k;
    }

    ll Math::powm(ll a, ll b) {
        ll res = 1;
        while (b > 0) {
            if (b & 1) (res *= a) %= mod;
            (a *= a) %= mod;
            b >>= 1;
        }
        return res;
    }

    bool Math::isPrime(ll n) {
        bool flg = true;
        for(ll i=2; i*i<=n; i++){
            if(n%i == 0) {
                flg = false;
                break;
            }
        }
        return flg;
    }

}

#endif //DEFINE_MATH_HPP

using math::Math;

class CSkip {
public:
	void solve(std::istream& in, std::ostream& out) {
	    ll n, X;
	    in >> n >> X;
	    vl x(n);
	    vl v;
	    Math mt;
	    for(int i=0; i<n; i++){
	        in >> x[i];
	        v.push_back(abs(x[i] - X));
	    }

        ll gcd = v[0];
	    for(int i=1; i<n; i++){
            gcd = mt.gcd(gcd, v[i]);
	    }

	    out << gcd << enl;
	}
};


int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
	CSkip solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 2168