import Control.Applicative ((<$>))
import Control.Monad (replicateM)
import Data.List (nub)

main :: IO ()
main = do
  w <- readLn
  h <- readLn
  n <- readLn
  solve w h n <$> replicateM n (map read <$> words <$> getLine) >>= print

solve :: Int -> Int -> Int -> [[Int]] -> Int
solve w h n sks = h * ls + w * lk - ls * lk - n
  where
    ls = length . nub . map (!! 0) $ sks
    lk = length . nub . map (!! 1) $ sks