open System

let arg = Console.ReadLine()

let separate (arg:string) =
  let rec splitStr (argStr:string) =
    match argStr.Length with
    | 0 -> ""
    | 1 | 2 | 3 -> argStr
    | _ -> argStr.Substring(0, (argStr.Length-3)) 
          |> splitStr  
          |> (fun split -> split + "," + argStr.Substring(argStr.Length-3))
  
  splitStr (arg)
  
printfn "%s" (arg |> separate)