import Control.Applicative
import Control.Monad

main :: IO ()
main = do
  n <- readLn
  cds <- replicateM n $ solve . map read . words <$> getLine
  print $ sum cds `mod` (10^9+7)

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