-- Input format: N X T
-- N: number of takoyaki to be created
-- X: number of takoyaki that can be created in one time period
-- T: time of one timeperiod (used above)
-- Return: time to make all takoyaki

module Main where

ans :: Int -> Int -> Int -> Int
ans n x t = 
	t * case n `mod` x of
		0 -> n `div` x
		_ -> 1 + (n `div` x)

main :: IO ()
main = getLine >>= 
	  putStrLn 
	. show 
	. (\(n:x:t:_) -> ans n x t)
	. map read
	. words
