p03625 AtCoder Beginner Contest 071 - Make a Rectangle
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
```python
N = int(input())
A = sorted([int(_) for _ in input().split()], reverse=True)

e = []
pre = 0
for i in range(N):
    if pre == A[i]:
        e.append(A[i])
        if len(e) >= 2: break
        pre = 0
    else:
        pre = A[i]
if len(e) < 2: print(0)
else: print(e[0] * e[1])
```