open System open System.Collections.Generic [] 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())) [] 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 ok i j k = i <> j && j <> k && i <> k let ok2 i j k = let l = [ i; j; k ] |> List.sort List.min l = j || List.max l = j let solve() = let n = read int let A = reada int let mutable cnt = 0 for i in 0 .. n - 3 do let a, b, c = A.[i], A.[i + 1], A.[i + 2] if (ok a b c) || (ok2 a b c) then cnt <- cnt + 1 puts cnt [] let main _ = try solve() with e -> printfn "%s" (e.ToString()) writer.Close() 0 // return an integer exit code