DouKaku?

object Miners extends Application {
  val N = readInt
  val foods = new Array[byte](N)
  for(i <- 0 until N) {
    def toNum(v:int):byte = {
      if(v == 'M') 1
      else if(v == 'F') 2
      else if(v == 'B') 3
      else error("ありえない")
    }
    foods(i) = toNum(System.in.read)
  }
  
  var sum = new Array[int](256)
  var sumNext = new Array[int](256)
  val kouho = List(0, 1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 15)
  for(i <- (0 until N).reverse) {
    val f = foods(i)
    for(l1 <- kouho) {
      for(l2 <- kouho) {
        def value(f:int, prev:int):int = {
          val p1 = prev % 4
          val p2 = prev / 4
          if(p1 == 0 && p2 == 0) {
            return 1
          } else if(p2 == 0) {
            if(p1 == f) return 1
            else return 2
          } else {
            //println("p1 = " + p1 + ", p2 = " + p2 + ", f = " + f)
            if(p1 == p2 && p2 == f) return 1
            else if(p1 != p2 && p2 != f && p1 != f) return 3
            else return 2
          }
        }
        val v1 = sum(((l1 % 4)*4 + f) * 16 + l2) + value(f, l1)
        val v2 = sum(l1 * 16 + ((l2 % 4)*4 + f)) + value(f, l2)
        sumNext(l1 * 16 + l2) = Math.max(v1, v2)
      }
    }
    val temp = sum
    sum = sumNext
    sumNext = temp
    //println(sum.toList)
  }
  println(sum(0))
}