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 defaultdict

d = defaultdict(int)

n = int(input())
a = list(map(int, input().split()))

ans = []
for i in a:
  d[i] += 1
  if d[i] == 2:
    d[i] = 0
    ans.append(i)
ans.sort(reverse=True)
if len(ans) >= 2:
  print(ans[0]*ans[1])
else:
  print(0)
