We have N sticks with negligible thickness. The length of the i-th stick is A_i.

Snuke wants to select four different sticks from these sticks and form a rectangle (including a square), using the sticks as its sides. Find the maximum possible area of the rectangle.

Constraints

* 4 \leq N \leq 10^5
* 1 \leq A_i \leq 10^9
* A_i is an integer.

Input

Input is given from Standard Input in the following format:


N
A_1 A_2 ... A_N


Output

Print the maximum possible area of the rectangle. If no rectangle can be formed, print 0.

Examples

Input

6
3 1 2 4 2 1


Output

2


Input

4
1 2 3 4


Output

0


Input

10
3 3 3 3 4 4 4 5 5 5


Output

20
import collections
n=int(input())
l=list(map(int,input().split()))
c=collections.Counter(l)
mc=c.most_common()
lec=sorted([i[0] for i in mc if i[1]>=4]+[i[0] for i in mc if i[1]>=2],reverse=True)
if len(lec)<=1:print(0);exit()
else:print(lec[0]*lec[1])