import Data.Maybe
import Data.List

main :: IO ()
main = do
  input <- getContents
  putStrLn $ trim (solve (trim input))

--処理
solve :: String -> String
solve s = show $ (n - 1) * (m - 1) where [n, m] = fmap read (words s) :: [Int]

trimHead :: String -> String
trimHead = dropWhile (\s -> isJust (elemIndex s [' ', '\t', '\n', '\r']))

trim :: String -> String
trim = reverse . trimHead . reverse . trimHead