import Control.Applicative
import Data.List
import Control.Monad
strToInteger s = (read :: String -> Integer) s

main :: IO ()
main = do
    -- スペース区切り整数の入力
    [n, h] <- map strToInteger . words <$> getLine
    ns <- replicateM (fromInteger n) $ do
        [a, b] <- map strToInteger . words <$> getLine
        return (a, b)
    -- 出力
    putStrLn $ show $ func ns n h

func :: [(Integer, Integer)] -> Integer -> Integer -> Integer
func ns n h = damage `div` hit + n + c
    where
        damage = (h - (sum $ map snd ns))
        hit = (fst . head $ sort ns)
        c = if damage `mod` hit == 0 then 0 else 1
