import Data.List
import Control.Monad

main = do 
  n <- readLn :: IO Int
  a <- replicateM n readLn :: IO [Int]
  print $ solve a

md :: Int
md = 10^9 + 7

type Stat = (Int, Int, Int, Int)

solve :: [Int] -> Int
solve a = let b = foldl' g [((i, j, i, j), 1) | i <- [0,1], j <- [0,1]] a
          in modsum . map snd . filter (\((h1, h2, x, y), _) -> h1 == x && h2 == y) $ b
  where
    g :: [(Stat, Int)] -> Int -> [(Stat, Int)]
    g acc a = compress (acc >>= f a)

    f :: Int -> (Stat, Int) -> [(Stat, Int)]
    f a ((h1, h2, x, y), cnt) = [((h1, h2, y, z), cnt) | z <- [0, 1], rule x y z == a]

compress :: [(Stat, Int)] -> [(Stat, Int)]
compress a = map f . groupBy (\x y -> fst x == fst y) $ a
  where
    f :: [(Stat, Int)] -> (Stat, Int)
    f x = let key = fst (head x); val = modsum . map snd $ x
          in (key, val)

modsum :: [Int] -> Int
modsum = foldl' (\x y -> (x + y) `mod` md) 0

rule :: Int -> Int -> Int -> Int
rule 0 0 0 = 0
rule 0 0 1 = 1
rule 0 1 0 = 1
rule 0 1 1 = 1
rule 1 0 0 = 0
rule 1 0 1 = 1
rule 1 1 0 = 1
rule 1 1 1 = 0