C. Chopsticks
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

There are $$$N$$$ pairs of chopsticks. The length of each chopstick of the $$$i^{th}$$$ pair is $$$l_i$$$ unit. Each chopstick is so thin that you can consider it as a line segment. Find the maximum area of the rectangle you can form by selecting two pairs of chopsticks.

Input

The first line contains an integer $$$N(2 \leq N \leq 100)$$$ — the number of pairs of chopsticks.

The next line contains $$$N$$$ integers $$$l_1,l_2,\dots,l_N\ (1 \leq l_1,l_2,\dots,l_N \leq 10^9) $$$ — the length of each pair of chopsticks.

Output

Output one integer $$$A$$$ — the maximum area possible in square units.

Examples
Input
3
1 2 3
Output
6
Input
4
1 2 3 3
Output
9
Note

In the first example, you pick the second and the third pair of chopsticks to form a rectangle of size $$$2 \cdot 3 = 6 $$$.

In the second example, you pick the third and fourth pair of chopsticks to form a rectangle of size $$$3 \cdot 3 = 9 $$$.