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()))
top1 = 0
top2 = 0
c = Counter()

for a in A:
    c[a] += 1
    if c[a] % 2 == 0:
        L = [a, top1, top2]
        L.sort()
        top1 = L[2]
        top2 = L[1]
print(top1 * top2)
