import qualified Data.ByteString.Lazy.Char8 as B
import Data.Maybe (fromJust)

maxExaminees :: [[Int]] -> Int
maxExaminees = mymod . mysum .
    map (\(c : d : _) -> mymod $ (*) (mymod d) $ mymod $ (c + 1) `div` 2)

mymod :: Int -> Int
mymod = (`mod` 1000000007)

mysum :: [Int] -> Int
mysum [] = 0
mysum (x : xs) = mymod x + mysum xs

main :: IO ()
main = getLine >> B.getContents >>= print .
    maxExaminees . map (map (fst . fromJust . B.readInt)) . map B.words . B.lines