fun main(args : Array<String>) {
    val x = readLine()!!.toLong()

    if (x <= 6) {
        println(1)
        return
    }

    if (x % 11 == 0L) {
        println((x / 11) * 2)
    } else if (x % 11 <= 6) {
        println((x / 11) * 2 + 1)
    } else {
        println((x / 11) * 2 + 2)
    }
}