import scala.math._

object HelloScala {
  def main(args: Array[String]): Unit = {
    val in = io.StdIn.readLine().split("")

    var cnt = 0

    for (e <- in){
      e match {
        case "0" => cnt += 1
        case _ =>
      }
    }

    println(abs(cnt - 8))

  }
}