open System

let rec insertions x = function
    | []             -> [[x]]
    | (y :: ys) as l -> (x::l)::(List.map (fun x -> y::x) (insertions x ys))

let rec permutations = function
    | []      -> seq [ [] ]
    | x :: xs -> Seq.concat (Seq.map (insertions x) (permutations xs))

let ri () = stdin.ReadLine() |> int
let ria () = stdin.ReadLine().Split() |> Array.map int

let isAscending (a:int list) = 
    a |> List.pairwise |> List.map (fun (x,y) -> x<y) |> List.reduce (fun s x -> s && x)

type Sol() =
    member this.Solve() = 
        let D = ria() |> Array.toList
        let permu = permutations D
        
        let ret = Seq.tryFind (fun ar -> ((isAscending (List.take 4 ar ) && (isAscending (List.skip 4 ar ))) = true )) permu
        if (Option.isSome ret) then "YES" else "NO"
        |> printfn "%s"
                                   
        
        
let mySol = new Sol()
mySol.Solve()