import Control.Applicative
import Control.Monad
import System.IO


main :: IO ()
main = do
    n_temp <- getLine
    let n_t = words n_temp
    let n = read $ n_t!!0 :: Int
    let m = read $ n_t!!1 :: Int
    print (n * m - 1)

getMultipleLines :: Int -> IO [String]

getMultipleLines n
    | n <= 0 = return []
    | otherwise = do          
        x <- getLine         
        xs <- getMultipleLines (n-1)    
        let ret = (x:xs)    
        return ret