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: Accepted)

N=parse(Int,readline())
A=map(x->parse(Int,x),split(readline()))
L=Array{Int}(0)
push!(L,0)
tmp=0
for i=A
	tmp=gcd(tmp,i)
	push!(L,tmp)
end
R=Array{Int}(0)
push!(R,0)
tmp=0
for i=reverse(A)
	tmp=gcd(tmp,i)
	push!(R,tmp)
end
R=reverse(R)
ans=0
for i=1:N
	ans=max(ans,gcd(L[i],R[i+1]))
end
println(ans)