package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
	return scanner
}
func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextUint64(scanner *bufio.Scanner) uint64 {
	i, _ := strconv.ParseUint(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	cnt := 0
	if os.Getenv("MASPY") == "ますピ" {
		fp, _ = os.Open(os.Getenv("BEET_THE_HARMONY_OF_PERFECT"))
		cnt = 5
	}
	if os.Getenv("MASPYPY") == "ますピッピ" {
		wfp, _ = os.Create(os.Getenv("NGTKANA_IS_GENIUS10"))
	}
	scanner := getScanner(fp)
	writer := bufio.NewWriter(wfp)
	solve(scanner, writer)
	for i := 0; i < cnt; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
	writer.Flush()
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	rr := make(robots, n)
	for i := 0; i < n; i++ {
		rr[i].x = getNextInt(scanner)
		rr[i].d = getNextInt(scanner)
	}
	sort.Sort(rr)

	dec := newDecomposition(n)
	for i := 0; i < n; i++ {
		dec.minimize(i, i)
	}
	dp := make([]mint, n+1)
	dp[0] = 1
	for i := 0; i < n; i++ {
		dp[i+1].addAs(dp[i])
		l := -1
		r := i
		for l+1 < r {
			m := (l + r) >> 1
			if rr[i].x+rr[i].d <= rr[m].x {
				l = m
				continue
			}
			r = m
		}
		if r < i {
			mn := dec.min(r, i)
			dp[i+1].addAs(dp[mn])
			dec.minimize(i, mn)
			continue
		}
		dp[i+1].addAs(dp[i])
	}
	fmt.Fprintln(writer, dp[n])
}

type robot struct {
	x, d int
}

type robots []robot

func (a robots) Len() int           { return len(a) }
func (a robots) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a robots) Less(i, j int) bool { return a[i].x > a[j].x }

type mint int64

func (mt mint) mod() mint {
	m := mint(998244353)
	mt %= m
	if mt < 0 {
		return mt + m
	}
	return mt
}
func (mt mint) inv() mint {
	var m, y mint
	m.subAs(2)
	dbl := mt
	y = 1
	for i := 0; i < 31; i++ {
		if m%2 == 1 {
			y.mulAs(dbl)
		}
		m >>= 1
		dbl.mulAs(dbl)
	}
	return y
}
func (mt mint) add(x mint) mint {
	return (mt + x).mod()
}
func (mt mint) sub(x mint) mint {
	return (mt - x).mod()
}
func (mt mint) mul(x mint) mint {
	return (mt * x).mod()
}
func (mt mint) div(x mint) mint {
	return mt.mul(x.inv())
}
func (mt *mint) addAs(x mint) *mint {
	*mt = mt.add(x)
	return mt
}
func (mt *mint) subAs(x mint) *mint {
	*mt = mt.sub(x)
	return mt
}
func (mt *mint) mulAs(x mint) *mint {
	*mt = mt.mul(x)
	return mt
}
func (mt *mint) divAs(x mint) *mint {
	*mt = mt.div(x)
	return mt
}

type decomposition struct {
	h, chunk int
	unit     []int
	bucket   [][]int
}

func newDecomposition(n int) decomposition {
	unit := make([]int, 1)
	unit[0] = 1
	bucket := make([][]int, 1)
	bucket[0] = make([]int, n)
	chunk := 8
	for i := 0; n > 1; i++ {
		n = (n-1)/chunk + 1
		bucket = append(bucket, make([]int, n))
		unit = append(unit, unit[i]*chunk)
	}
	return decomposition{
		h:      len(unit),
		chunk:  chunk,
		unit:   unit,
		bucket: bucket,
	}
}
func (dec *decomposition) minimize(index int, value int) {
	dec.bucket[0][index] = value
	for i := 0; i < dec.h-1; i++ {
		p := index / dec.chunk
		r := (p + 1) * dec.chunk
		if r >= len(dec.bucket[i]) {
			r = len(dec.bucket[i])
		}
		dec.bucket[i+1][p] = value
		for j := p * dec.chunk; j < r; j++ {
			if dec.bucket[i+1][p] > dec.bucket[i][j] {
				dec.bucket[i+1][p] = dec.bucket[i][j]
			}
		}
		index /= dec.chunk
	}
}
func (dec *decomposition) min(l, r int) int {
	return dec.minh(l, r, 0)
}

func (dec *decomposition) minh(l, r, h int) int {
	m := dec.bucket[h][l]
	ll := (l + dec.chunk - 1) / dec.chunk
	rr := r / dec.chunk
	for i := l; i < r && i < ll*dec.chunk; i++ {
		if m > dec.bucket[h][i] {
			m = dec.bucket[h][i]
		}
	}
	if ll < rr {
		mm := dec.minh(ll, rr, h+1)
		if m > mm {
			m = mm
		}
	}
	for i := rr * dec.chunk; i < r; i++ {
		if i < l {
			continue
		}
		if m > dec.bucket[h][i] {
			m = dec.bucket[h][i]
		}
	}
	return m
}


Measured memory_bytes: 11008