Maximum Value
Description
You are given a sequence a consisting of n integers. Find the maximum possible value of 
(integer remainder of ai divided by aj), where 1 ≤ i, j ≤ n and ai ≥ aj.
The first line contains integer n — the length of the sequence (1 ≤ n ≤ 2·105).
The second line contains n space-separated integers ai (1 ≤ ai ≤ 106).
Print the answer to the problem.
Input
The first line contains integer n — the length of the sequence (1 ≤ n ≤ 2·105).
The second line contains n space-separated integers ai (1 ≤ ai ≤ 106).
Output
Print the answer to the problem.
Samples
3
3 4 5
2