price :: [Int] -> Int
price = iter 0 [] where
iter m l [] = div m 2 + sum l
iter m l (x:xs)
| x > m     = iter x (m:l) xs
| otherwise = iter m (x:l) xs

readData :: Int -> IO [Int]
readData 0 = return []
readData n = do
x <- readLn :: IO Int 
fmap (x:) $ readData (n-1)

main :: IO() 
main = do
n <- readLn :: IO Int
l <- readData n
let ans = price l 
print ans
