open System

let solve (n: string) =
  let f = n.Substring(0, 1)
  let e = n.Substring(1)
  let ea = e.ToCharArray()
  if f = "1" && (ea |> Array.forall((=) '3')) then
    ea |> Array.length
  else -1

let N = Console.ReadLine()

solve N
|> Console.WriteLine