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(raw_input())
l = map(int, raw_input().split())
c = Counter(l)
ls = sorted(c.keys(), reverse=True)
h = 0
w = 0
for k in ls:
    if c[k] >= 4 and h == 0 and w == 0:
        h = k
        w = k
        break
    elif c[k] >= 2:
        if h == 0:
            h = k
        else:
            w = k
            break
print h*k
