open System
open System.Collections.Generic

[<AutoOpen>]
module Cin =
    let read f = stdin.ReadLine() |> f
    let reada f = stdin.ReadLine().Split() |> Array.map f
    let readChars() = read string |> Seq.toArray
    let readInts() = readChars() |> Array.map (fun x -> Convert.ToInt32(x.ToString()))

[<AutoOpen>]
module Cout =
    let writer = new IO.StreamWriter(new IO.BufferedStream(Console.OpenStandardOutput()))
    let print (s: string) = writer.Write s
    let println (s: string) = writer.WriteLine s
    let inline puts (s: ^a) = string s |> println

// -----------------------------------------------------------------------------------------------------

// -----------------------------------------------------------------------------------------------------

let main() =
    let N = read int
    let A = reada int64
    let mutable ok = true
    for i in 0 .. N - 1 do
        match i with
        | _ when i = N - 2 ->
            if A.[N - 2] <> A.[N - 1] ^^^ A.[0] then ok <- false
        | _ when i = N - 1 ->
            if A.[N - 1] <> A.[0] ^^^ A.[1] then ok <- false
        | _ ->
            if A.[i] <> A.[i + 1] ^^^ A.[i + 2] then ok <- false

    if ok then "Yes" else "No"
    |> puts
    ()

// -----------------------------------------------------------------------------------------------------
main()
writer.Dispose()
