import scala.annotation.tailrec
object Solution {

  @tailrec
  def countvalleys(w:List[Char], l:Int, cnt:Int):Int = w match {
    case Nil => cnt
    case x::xs => countvalleys(xs, if (x=='D') l-1 else l+1, if (x=='D' && l == 0) cnt+1 else cnt)
  }

  def main(args: Array[String]) {
    readLine
    val s = readLine
    if (s != null) {
      println(countvalleys(s.toList, 0, 0))        
    }
  }
}