object Main extends App{
    def readLine() = io.StdIn.readLine()
    
    val n = readLine().toInt
    val robots = Iterator.continually(readLine()).take(n).map(_.split(' ').map(_.toLong)).map {
        case Array(x, l) => (x, l)
    }.toSeq.sortBy(_._1)

    
    def removeRobots(robots: Seq[(Long, Long)]): Seq[(Long, Long)] = {
        val interferences = robots.map {
            case (x, l) =>
                val interference = robots.dropWhile {
                    case (xa, la) => xa <= x - l
                }.takeWhile {
                    case (xb, lb) => xb < x + l
                }.length
                (x, l, interference)
        }
        val maxInterference = interferences.maxBy(_._3)
        if (maxInterference._3 == 1)
            robots
        else
            removeRobots(interferences.withFilter(_ != maxInterference).map {
                case (x, l, interference) => (x, l)
            })
    }

    val answer = removeRobots(robots)
    
    println(answer.length)
}
