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())
a=list(map(int,input().split()))
x1=0
x2=0
count=Counter(a)
for i in count:
  if count[i]>=4:
    if x1<=i:
      x2=i
      x1=i
  if count[i]>=2:
    if x1<=i:
      x2=x1
      x1=i
    elif x2 <= i < x1:
      x2=i
print(x1*x2)