fun main(args: Array<String>) {
    arc068c()
}

fun arc068c() {
    val x = readLine()!!.toLong()

    val answer = if (x <= 6) 1 else if (x <= 11) 2 else 1 + Math.ceil((x - 6).toDouble() / 5.5).toLong()

    println(answer)
}
