import Data.Functor
import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe

countExaminee :: [[Int]] -> Int
countExaminee (_:xs) = count xs `mod` 1000000007
  where
    count :: [[Int]] -> Int
    count [] = 0
    count ((c:d:_):xs) = ((c' + 1) `div` 2) * d' + count xs
      where
        c' = c `mod` 1000000007
        d' = d `mod` 1000000007

readInts :: B.ByteString -> [Int]
readInts s = fst <$> mapMaybe (B.readInt) (B.words s)

main :: IO ()
main = countExaminee <$> (readInts <$>) <$> B.lines <$> B.getContents >>= putStrLn . show