### Problem Statement

A DNA molecule is formed by two nucleotide chains of equal length. Each nucleotide in the first chain must form a bond with the nucleotide at the same position in the second chain. There are four types of nucleotides: A, C, G and T. Each type of nucleotide can only form a bond with one other type: A can only bond with T, and G can only bond with C. These pairs, AT and CG, are called complementary pairs. No other bonds are allowed.

You are given a String nucleotides, where each character is an available nucleotide. Return the length of the longest DNA molecule that can be created using only the available nucleotides. The length of a DNA molecule is the number of nucleotides in either one of its chains. If no DNA molecule can be created, return 0.

### Definition

 Class: DNAConstruction Method: maxLength Parameters: String Returns: int Method signature: int maxLength(String nucleotides) (be sure your method is public)

### Notes

-For the purposes of this problem we assume that there is no restriction for the set of nucleotides in each DNA chain.

### Constraints

-nucleotides will contain between 1 and 50 characters, inclusive.
-Each character in nucleotides will be 'A','C','G' or 'T'.

### Examples

0)

 `"AGGCA"`
`Returns: 1`
 The set of nucleotides contains only one complementary pair CG.
1)

 `"GGTACAGTTT"`
`Returns: 3`
 The set of nucleotides contains one CG pair and two AT pairs.
2)

 `"ACCACCAACCA"`
`Returns: 0`
 The set of nucleotides contains only A and C nucleotides, which aren't complementary.
3)

 `"AAAAAAAAAAAAAAAAACCCCCCCCGGGGGGGGTTTTTTTTTTTTTTTTT"`
`Returns: 25`

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=9818

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=13486&pm=9818

Nickolas

#### Testers:

PabloGilberto , Olexiy , ivan_metelsky

Simple Math