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
from collections import Counter

n=int(input())
l=[int(i) for i in input().split()]
c=Counter(l).most_common()
s=sorted([key,val] for key,val in c if val>=2)

if len(s)<2:
    ans=0
elif s[-1][1]>=4:
    ans=s[-1][0]**2
else:
    ans=s[-1][0]*s[-2][0]

print(ans)
