import java.util.*

fun main(args: Array<String>) {
    val scanner = Scanner(System.`in`)
    val N = scanner.nextLong()
    
    val even = (N - 1) / 11 * 2 + 2
    val odd = (N + 4) / 11 * 2 + 1
    
    println(if(even < odd) even else odd)
}