Akash loves writing with red or green pen and to impress him his friend Kiran buys him N pens of 'red' or 'green' colors but Akash isn't happy
to see two coloured pens ,he wants all N pen of same color either 'red' or 'green'.He requested Kiran for the exchange of M pens(from the shop)
so that he can have all N pens of same color i.e. either 'Red' or'Green.
Help kiran to find the minimum number of pens(M) she should ask for the exchange from the shopkeeper.
The first line of input contains an integer T denoting the number of test cases . Next line of input contains a positive number N
denoting the number of pens Kiran buys for Akash and the next line of input contains the string sequence of N pen colours-R for 'Red' and 'G' for 'green'.
For each test case , the output is in a new line containg an integer M which is the minimum number of pens Kiran has to exchange.
Kiran can ask for the exchange of two green pens with red pens,thereby,making all 5 pens of red colour.
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