## Play with words

Shaka and his brother have created a boring game which is played like this:

They take a word composed of lowercase English letters and try to get the maximum possible score by building exactly 2 **palindromic subsequences**. The score obtained is the product of the length of these 2 subsequences.

Let's say and are two subsequences from the initial string. If & are the smallest and the largest positions (from the initial word) respectively in ; and & are the smallest and the largest positions (from the initial word) respectively in , then the following statements hold true:

,

, &

.

i.e., the positions of the subsequences should not cross over each other.

Hence the score obtained is the product of lengths of subsequences & . Such subsequences can be numerous for a larger initial word, and hence it becomes harder to find out the maximum possible score. Can you help Shaka and his brother find this out?

**Input Format**

Input contains a word composed of lowercase English letters in a single line.

**Constraints**

each character will be a lower case english alphabet.

**Output Format**

Output the maximum score the boys can get from .

**Sample Input**

```
eeegeeksforskeeggeeks
```

**Sample Output**

```
50
```

**Explanation**

A possible optimal solution is **eee**-g-**ee**-ksfor-**skeeggeeks** being **eeeee** the one subsequence and **skeeggeeks** the other one. We can also select **eegee** in place of **eeeee**, as both have the same length.