### Problem Statement

There are some cards placed in a line. Each card is characterized by the three distinct letters written on it.

The conformity-level of two cards is the number of distinct letters that are common to both cards. For example, the conformity-level of "ABC" and "ACD" is 2 because the letters 'A' and 'C' are common to both cards, and the conformity-level of "ABC" and "DFE" is 0 because the two cards share no common letters.

You can remove a card if the conformity-level of its left neighbor and its right neighbor is greater than or equal to 2. Once a card is removed its left and right neighbors become neighbors themselves. The leftmost and rightmost cards are never removed.

Given a String[] cards, determine the maximum quantity of cards that you can remove.

### Definition

 Class: CardRemover Method: calculate Parameters: String[] Returns: int Method signature: int calculate(String[] cards) (be sure your method is public)

### Constraints

-cards will have between 2 and 50 elements, inclusive.
-Each element of cards will contain exactly 3 characters.
-Each element of cards will contain three distinct uppercase letters ('A'-'Z').

### Examples

0)

 ```{"ABC", "CDE", "ABC", "CDE", "ABC"} ```
`Returns: 3`
 You should not remove the third card before the second or the fourth.
1)

 ```{"ABC", "CDE", "EFG", "GHI", "IJK"} ```
`Returns: 0`
 You can't remove anything.
2)

 ```{"ADR", "FDB", "ABC", "CDE", "ABD"} ```
`Returns: 3`

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=4468

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=8012&pm=4468

Andrew_Lazarev

#### Testers:

PabloGilberto , lbackstrom , brett1479 , Olexiy

#### Problem categories:

Dynamic Programming