### Problem Statement

There are N students standing in a single row, one next to the other, numbered 0 to N-1 from left to right. Your goal is to minimize the number of adjacent pairs where one student is a boy and the other is a girl. More precisely, you want to minimize the number of values i, 0 <= i < N-1, where student i and student i+1 are of different genders.

You are given the current arrangement as a String row, where the i-th character is 'G' if student i is a girl, and 'B' if student i is a boy. In a single move, you can choose two adjacent students and swap their positions. Return the minimum number of moves required to achieve your goal.

### Definition

 Class: GirlsAndBoys Method: sortThem Parameters: String Returns: int Method signature: int sortThem(String row) (be sure your method is public)

### Constraints

-row will contain between 1 and 50 characters, inclusive.
-Each character in row will be 'G' or 'B'.

### Examples

0)

 `"GGBBG"`
`Returns: 2`
 You can swap the rightmost girl with the two boys (one after the other) to get "GGGBB", with a minimum of only 1 pair of adjacent students of different gender.
1)

 `"BBBBGGGG"`
`Returns: 0`
 There is already a single pair of adjacent students of different gender, and there is no arrangement without such pairs at all, so the best solution is to swap nothing.
2)

 `"BGBGBGBGGGBBGBGBGG"`
`Returns: 33`
3)

 `"B"`
`Returns: 0`
 With only one student, there is not much swapping to do.

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=7794

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=14294&pm=7794

soul-net

#### Testers:

PabloGilberto , ivan_metelsky

Greedy