import Control.Monad

solve3 _ _ [] = 1001
solve3 g i ([p,c]:pcs)
  | g <= 0 = 0
  | g <= p*i*100 = min p (solve3 g (i-1) pcs)
  | g <= p*i*100+c = min p (solve3 g (i-1) pcs)
  | otherwise = min (p + solve3 (g-p*i*100-c) (i-1) pcs) (solve3 g (i-1) pcs)

main = do
  [d,g] <- map read . words <$> getLine
  list <- replicateM d $ map read . words <$> getLine
  putStrLn . show $ solve3 g d list
