import Data.List
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = breads >>= print . solve 

solve :: [Int] -> Int
solve [n, m]
    | n > 1 && m > 1 = n * m - (n + m) * 2 + 4
    | n == 1 && m == 1 = 1
    | otherwise = n * m - 2

breads :: IO [Int]
breads = unfoldr uff <$> B.getLine
    where
        uff b = check <$> B.readInt b
        check (a, b)
            | B.null b = (a, b)
            | otherwise = (a, B.tail b)