Xenny was a teacher and his class consisted of N boys and N girls. He took all his students to the playground and asked them to stand in a straight line. The boys and the girls formed a perfect line, but Xenny seemed unhappy. He wanted them to form an alternating sequence of boys and girls, i.e., he wanted that after a boy, there should be a girl in the line, and vice-versa.

In order to form an alternating sequence, a boy and a girl could swap their positions.

Given the original sequence in which the boys and girls were standing, find the minimum number of swaps required to form an alternating sequence.

Note: An alternating sequence can start either with a boy or a girl.

Input

First line of input consists of a natural number T - the number of testcases.
T testcases follow. For each testcase:

First line consists of a single integer N - the number of boys, and the number of girls.
Second line consists of a string of length $2N$, representing the original sequence.
In this string, a boy is represented by uppercase character B and a girl by G.

Output

For each testcase, print the minimum number of swaps required to get an alternating sequence on a new line.

Constraints

$1 \le T \le 5$

$1 \le N \le 10^6$

Subtasks

1. $1 \le N \le 20$ : 10 points
2. $1 \le N \le 10^6$ : 90 points