import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Lazy.Char8 as B
import Data.Maybe

main :: IO ()
main = do
  getLine
  cds <- map (solve . map (fst . fromJust . B.readInteger) . B.words) . B.lines <$> B.getContents
  print $ sum cds `mod` (10^9+7)

solve :: [Integer] -> Integer
solve [c,d]
  | c <= 2    = d
  | otherwise = 2*d