func compress(input: String) -> String {
    var input = input
    var count = 1
    var output = ""
    for char in input {
        if let last = output.last, last == char {
            count += 1
        }else {
            if count > 1 {
                output = output + String(count)
                count = 1
            }
            output = output + String(char)
        }
    }
    if count > 1 {
        output = output + String(count)
    }
    return output
}

    val s: String = io.StdIn.readLine().trim

    val chars: Seq[String] = Seq(
      "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l",
      "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "x", "w", "y", "z"
    )

    val groupPattern: Regex = chars.map(c => s"($c{2,})").reduce(_ + "|" + _).r

    val compressed: String = groupPattern.findAllIn(s).toVector
      .sortBy(_.length * -1)
      .foldLeft(s){ (acc, group) =>
        acc.replace(group, s"${group.head}${group.length}")
      }

    println(compressed)

let rec compress n list =
    match list with
    | [] -> []
    | [ c ] when n = 1 -> [ c ]
    | [ c ] -> [ c; string n ]
    | x :: xs when x = List.head xs -> compress (n + 1) xs
    | x :: xs when n = 1 -> x :: compress 1 xs
    | x :: xs -> x :: string n :: compress 1 xs

open System

[<EntryPoint>]
let main _ =
    Console.ReadLine()
    |> Seq.toList
    |> List.map string
    |> compress 1
    |> String.concat ""
    |> Console.WriteLine

    0