Problem:
Score : 300 points

Problem Statement

There are N integers, A_1, A_2, ..., A_N, written on the blackboard.

You will choose one of them and replace it with an integer of your choice between 1 and 10^9 (inclusive), possibly the same as the integer originally written.

Find the maximum possible greatest common divisor of the N integers on the blackboard after your move.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq A_i \leq 10^9

Output

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the maximum possible greatest common divisor of the N integers on the blackboard after your move.

Sample Input 1

3
7 6 8

Sample Output 1

2

If we replace 7 with 4, the greatest common divisor of the three integers on the blackboard will be 2, which is the maximum possible value.

Sample Input 2

3
12 15 18

Sample Output 2

6

Sample Input 3

2
1000000000 1000000000

Sample Output 3

1000000000

We can replace an integer with itself.

Solution in Julia (0.5.0) (judge verdict: Wrong Answer)

parseInt(x)=parse(Int,x)
parseMap(x::Array{SubString{String},1})=map(parseInt,x)
function bsearch(a::Array{Int,1},x::Int);l,r=1,length(a);while l<=r;m=l+div(r-l,2);if a[m]<x;l=m+1;else;r=m-1;end;end;return(l-1);end

function main()
	n = readline() |> parseInt
	a = readline() |> split |> parseMap
	if length(a) == 2
		println(maximum(a))
	else
		k = Array{Int}(n)
		for i in 1:n-1
			k[i] = gcd(a[i],a[i+1])
		end
		k[n] = gcd(a[n],a[1])
	    tmp = k[n]
		for i in 0:n-2
			k[n-i] = k[n-i-1]*k[n-i]
		end
		k[1] = tmp*k[1]
		x = indmin(k)
		deleteat!(a,x)
		println(gcd(a))	
	end
end
main()