import scala.io.StdIn.readLine

object Main extends App {
  val Array(a, b, c) = readLine.split(" ").map(_.toInt)
  var coin = 0
  var login = 0
  while (coin < c) {
    coin += a
    login += 1
    if (login % 7 == 0) {
      coin += b
    }
  }
  println(login)
}

