open System

let read() = Console.ReadLine() |> int
let out flag = 
        if flag then printfn "T"
        else         printfn "F"                

let N = read()
let X = 0 :: List.init N (fun _ -> read()) 
        |> Array.ofList
                        
Array.map2 (fun l r -> abs (l - r)) X.[0 .. N-1] X.[1 .. N]
|> Array.forall(fun x -> x = 1)
|> out