hzau 1207 Candies

     Xiao Ming likes those N candies he collects very much. There are two kinds of candies, A and B. One day, Xiao Ming puts his candies in a row and plays games. And he can replace the Lth candy to the Rth candy with the same kind of candies. Now, he wonder that if he eats the Lth candy to Rth candy, he can eat how many B candy continuously at most. For each Xiao Ming’s query, give the number of the B candy he can eat continuously at most. 

     In the first line, there is an integer T, indicates the number of test cases.

     For each case, there are two integers N and M in the first line, indicate the number of candies and the time of Xiao Ming’s operations.

     The second line is a N-length string consist of character A and B, indicates the row of candies Xiao Ming put.

     The next M line is Xiao Ming’s operations. There are two kind of operations:

          1. 1 L R v, indicate Xiao Ming replaces the Lth candy to the Rth candy with A candies (v==1) or B candies ( v == 2 ).

          2. 2 L R, indicate Xiao Ming wonder that there are how many continuous B candies between the Lth candy to the Rth candy most. 

       In each case, the first line is “Case #k: “, k indicates the case number.

      For each query, output the number of the most continuous B candies.