You are given an integer R, and an array A consisting of positive integers.
You can do this operation at most once (possibly zero times):
• Choose any element of the array. Replace it with any integer X, such that 1<= X ≤ R.
Find the maximum possible GCD of the entire array.
2<=N<=10^5 (N is length of array)
1<=R<=10^5
1<=Ai<=10^5

Example: A = [2,3,4] and R=10
Output: 2
Explanation: We can change the second element from 3 to 2. Then GCD of the array becomes gcd(2,2,4)=2, which is the maximum possible.