import Control.Monad -- for replicateM_
import Data.List -- for sort


{-
deal :: IO()
deal = do 
    [n, x] <- map read . words <$> getLine
    info <- replicateM (n-1) getWeight
    -- graph <- buildTree info [[[]]]
    putStrLn $ show info

main :: IO()
main = getLine >>= flip replicateM_ deal . read 
-}

solve :: Int -> Int -> Int -> Int
solve n x t = t * (ceiling $ toRational (realToFrac n / (realToFrac x)))

main :: IO()
main = do 
    [n, x, t] <- map read . words <$> getLine
    putStrLn $ show $ solve n x t
