object Solution {

    def main(args: Array[String]) {
        scala.io.StdIn.readLine
        val input = scala.io.StdIn.readLine
        val res = input.foldLeft((0, 0)){ case ((level, count), c) =>
            if (c == 'D') (level-1, if (level == 0) count+1 else count)
            else (level+1, count)
        }
        println(res._2)
    }
}