You are given an array $A$ of length $n$. Find the maximum value of $a_i \times a_j$ and $i < j$.
### Input
- The first line contains an integer $n$.
- The second line contains $n$ integers $A_i$.
### Output
- Print a single integer which is maximum value possible.
### Constraints
- $1 \le n \le 10^3$.
- $|A_i| \le 1000 $.
### Example
Input:
```
4
-2 -10 3 4
```
Output:
```
20
```
