module lib1

let allLines = seq{
    let mutable line = System.Console.ReadLine()
    while line <> null do
        yield line
        line <- System.Console.ReadLine()
}

let mutable line = System.Console.ReadLine()

let data = 
    allLines
    |> Seq.map (fun l ->
        int l
    )
    |>Seq.sort
    |>Seq.fold (fun s t ->
        match snd s with
        |Some b when b = t -> s
        |_ -> (fst s + 1, Some t)
    ) (0, None)
    |> fst

System.Console.WriteLine(data)
