#!/usr/bin/env fsharpi

open System;

let ParseIntN ( str : string ) =
    str.Split(' ')
    |> Array.map System.Int32.Parse

let ParseInt1 ( str : string ) =
    ParseIntN str |> fun arr -> arr.[0]

let ParseInt2 ( str : string ) =
    ParseIntN str |> fun arr -> (arr.[0],arr.[1])

let ParseInt3 ( str : string ) =
    ParseIntN str |> fun arr -> (arr.[0],arr.[1],arr.[2])

let ReadLinesN ( n : int ) =
    fun _ -> Console.ReadLine()
    |> Seq.initInfinite
    |> Seq.take n

let ReadLines =
    fun _ -> Console.ReadLine()
    |> Seq.initInfinite
    |> Seq.takeWhile ((<>) null)

module String =
    /// Converts a string into a list of characters.
    let explode (s:string) =
        [for c in s -> c]

    /// Converts a list of characters into a string.
    let implode (xs:char list) =
        let sb = System.Text.StringBuilder(xs.Length)
        xs |> List.iter (sb.Append >> ignore)
        sb.ToString()

let rec doit acc s =
    match s with
    | 'B'::t when acc = [] -> doit acc t
    | 'B'::t -> doit (List.tail acc) t
    | h::t -> doit (h::acc) t
    | [] -> List.rev acc

Console.ReadLine()
|> String.explode
|> doit []
|> String.implode
|> Console.WriteLine
