C++ Skip | AtCoder

Time Limit: 2 sec / Memory Limit: 1024 MB

Problem Statement

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

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≤N≤10^5
• 1≤X≤10^9
• 1≤xi​≤10^9
• xi​ are all different.
• x1​,x2​,...,xN​!=X

In