import Control.Monad
import Control.Applicative
import Data.List
import qualified Data.Map as Map
import qualified Data.ByteString.Char8 as BC
import Data.Array
import Data.Maybe


strToInt s = (read :: String -> Int) s
readInt :: BC.ByteString -> Int
readInt = fst . fromJust . BC.readInt


main = do
    n <- readLn :: IO Int
    cd <- map ((map readInt . BC.words)) <$> replicateM n BC.getLine
    print $ f cd
    
f :: [[Int]] -> Int
f [] = 0
f (a:an) = mod ((f an) + (g (head a)) * (last a)) 1000000007
            where g x = if (even x)
                        then div x 2
                        else (div x 2) + 1