let calc (a: int[]) =
    let parity = a.[0] &&& 1
    let a_sorted = Array.append (Array.sort a) [| -1 |]
    let index = [| 1 .. a_sorted.Length - 1 |]

    if (Array.exists (fun x -> a_sorted.[x] - a_sorted[x - 1] = 1) index) then
        2
    else
        1

let main =
    let n = stdin.ReadLine() |> int

    let e =
        [| for i = 0 to n - 1 do
               stdin.ReadLine() |> int |]

    printfn "%d" (calc e)
    0