main:: IO ()
main = do
  nc<-getLine
  let n = read nc ::Integer
  print (solver n)

solver::Integer -> Integer
solver x = let turn_56 = (div x 11)*2 in
           let rest    =  mod x 11    in
           if x == 0 then 0 else (turn_56 + if rest <= 6 then 1 else 2)