import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as BS
import Data.List
import Data.Tuple

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
getInt = readInt <$> BS.getLine
getIntList = readIntList <$> BS.getLine

main = do
    n <- getInt
    arms <- replicateM n $ do
        [x,l] <- getIntList
        return (x-l,x+l)
    print . solve (- 10^9) $ sortOn swap arms

solve _ [] = 0
solve m ((l,r):xs) | m <= l = 1 + solve r xs
                   | otherwise = solve m xs