Description
time limit per test
1 secondmemory limit per test
256 megabytesinput
standard inputoutput
standard outputYou 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.
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.
Examples
Input
3
3 4 5
Output
2