object Main extends App {
    val in = io.Source.stdin.getLines.map(_.toInt).toList.init
    in.foreach{m =>
        val x = Array(0, 0)
        def s(n: Int): Unit =
            if(n%2 == 0) {x(0) += 1; s(n/2)}
            else if(n%5 == 0) {x(1) += 1; s(n/5)}
        (2 to m).foreach(s)
        println(x(0) min x(1))
    }
}