let zeroCount (str:string) =
    str.ToCharArray()
    |> Array.where(fun c -> c = '0')
    |> Array.length

let roleModel = "1000000007"
let roleModel'sZeroCnt = roleModel |> zeroCount

let N = stdin.ReadLine()
let N'sZeroCnt = N |> zeroCount

abs(roleModel'sZeroCnt - N'sZeroCnt) |> printfn "%i"