import Data.List
import qualified Data.ByteString.Char8 as B
import Control.Monad

main :: IO ()
main = readLn >>= flip replicateM breads >>= print . solve

solve :: [[Int]] -> Int
solve = foldl' ff 0
    where
        ff acc [l, r] = acc + r - l + 1

breads :: IO [Int]
breads = unfoldr uff <$> B.getLine
    where
        uff b = check <$> B.readInt b
        check (a, b)
            | B.null b = (a, b)
            | otherwise = (a, B.tail b)
