let x = stdin.ReadLine () |> Seq.sortDescending |> Seq.map string |> String.concat ""

if x.Length = 1 || (x.Length = 2 && x.[1] = '0') || Seq.forall ((=)x.[0]) x then
    "-1"
else
    let mutable index = x.Length - 2
    while x.[index] = x.[index+1] do
        index <- index - 1
    (if index = 0 then "" else x.[..index-1]) + string x.[index+1] + string x.[index] + x.[index+2..]
|> printfn "%s"