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())
a = [int(i) for i in input().split()]
l = collections.Counter(a)
l_ = [k for k, v in l.items() if v > 1]
if len(l_) > 1:
    l_.sort()
    if l[l_[-1]] > 3:
        print(l_[-1]**2)
    else:
        print(l_[-1]*l_[-2])
else:
    print(0)