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

inputFormat

Input

Input is given from Standard Input in the following format:

N A_1 A_2 ... A_N

outputFormat

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

样例

10
3 3 3 3 4 4 4 5 5 5

20