import Control.Monad

main = do
  n <- readLn :: IO Int
  -- cs <- map (map read . words) <$> replicateM n getLine
  cs <- replicateM n $ (map read . words) <$> getLine
  putStrLn . show $ (solve cs) `mod` (10^9+7)
  
solve :: [[Int]] -> Int
solve xs = sum $ map fn xs
  where fn [x, y] = if even x then x `div` 2 * y else (x `div` 2 + 1) * y