## Palindromic Deletion

#### Palindromic Deletion

Albert's many years of competitive programming have addled his brain to the point where he loves palindromes and has signed up to a palindromic challenge (I know, its a sad point to get to). Every week, he gets a string of uppercase, alphabetic characters in the mail and has to delete a substring and send the modified string back as a palindrome. Because he is a "serious" programmer, he'd like to send the longest palindrome that he can.

#### Input Specification

The first line will contain the number \(N\), the length of the string to follow. The following line will contain a string of \(N\) uppercase letters.

#### Output Specification

Print the length of the longest palindrome Albert can make.

#### Bounds

This problem has three sub-problems of varying difficulty.

- 30 points: \(0 \leq N \leq 50\)
- 70 points: \(50 < N \leq 3000\)
- 100 points: \(3000 < N \leq 10^5\)

#### Example Input

```
3
ABA
```

#### Example Output

`3`

#### Example Input

```
3
AAB
```

#### Example Output

`2`

## Comments