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
n=int(input())
dic=dict()
l=list(map(int,input().split()))
for i in l:
	if i not in dic.keys():
		dic[i]=1
	else:
		dic[i]+=1
p=[k for k,v in dic.items() if v>=2]
f=0
s=0
for i in p:
	if i>f:
		f,s=i,f
	elif i>s:
		s=i
print(0 if f==0 else f**2 if dic[f]>=4 else f*s)