kadomatsu :: [Int] -> Int
kadomatsu [x,y] = 0
kadomatsu (x:y:z:ts) = f + kadomatsu (y:z:ts) where
    f   | (maximum [x,y,z] == y || minimum [x,y,z] == y) && x /= z  = 1
        | otherwise = 0

main = do
    getLine
    ts <- map read . words <$> getLine
    print $ kadomatsu ts