#![allow(unused_imports, unused_macros, dead_code)]

macro_rules! min {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        it.next().map(|z| it.fold(z, |x, y| min!(x, y)))
    }};
    ($x:expr) => ($x);
    ($x:expr, $($ys:expr),*) => {{
        let t = min!($($ys),*);
        if $x < t { $x } else { t }
    }}
}
macro_rules! max {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        it.next().map(|z| it.fold(z, |x, y| max!(x, y)))
    }};
    ($x:expr) => ($x);
    ($x:expr, $($ys:expr),*) => {{
        let t = max!($($ys),*);
        if $x > t { $x } else { t }
    }}
}
macro_rules! ewriteln {
    ($($args:expr),*) => { let _ = writeln!(&mut std::io::stderr(), $($args),*); };
}
macro_rules! trace {
    ($x:expr) => { ewriteln!(">>> {} = {:?}", stringify!($x), $x) };
    ($($xs:expr),*) => { trace!(($($xs),*)) }
}
macro_rules! put {
    (.. $x:expr) => {{
        let mut it = $x.iter();
        if let Some(x) = it.next() { print!("{}", x); }
        for x in it { print!(" {}", x); }
        println!("");
    }};
    ($x:expr) => { println!("{}", $x) };
    ($x:expr, $($xs:expr),*) => { print!("{} ", $x); put!($($xs),*) }
}

const M: i64 = 998244353;

/// 降順 xs について z 未満の最小添字を返す
fn bisearh(xs: &Vec<(i64, i64)>, z: i64) -> usize {
    let n = xs.len();
    if xs[0].0 < z { return 0 }
    let mut left = 0;  // xs[left] >= z
    let mut right = n;  // xs[right] < z
    for _ in 0..100 {
        let mid = (left + right) / 2;
        if xs[mid].0 >= z {
            left = mid;
        } else {
            right = mid;
        }
    }
    right
}

fn main() {
    let mut sc = Scanner::new();
    let n: usize = sc.cin();
    let mut rs: Vec<_> = (0..n).map(|_| {
        let x: i64 = sc.cin();
        let d: i64 = sc.cin();
        (x, d)
    }).collect();
    rs.sort(); rs.reverse();
    // trace!(&rs);

    // st[i] = i 番目を起動した場合に起動する最小の番目
    let mut st = SegmentTree::new(n);
    st.update(0, MinInt::Val(0));
    {
        for i in 1..n {
            st.update(i, MinInt::Val(i));
            let (x, d) = rs[i];
            let k = bisearh(&rs, x + d);
            if let MinInt::Val(l) = st.product(k..i + 1) {
                st.update(i, MinInt::Val(l));
            }
            // trace!(i, k, st[i]);
        }
    }

    // dp[i][0] = i を起動しない 場合の 0..i の動かし方
    // dp[i][1] = i を起動する   場合の 0..i の動かし方
    let mut dp = vec![vec![ModInt(0, M); 2]; n];
    dp[0][0] += 1;
    dp[0][1] += 1;
    for i in 1..n {
        dp[i][0] = dp[i - 1][0] + dp[i - 1][1];
        let k = st[i].unwrap();
        dp[i][1] = if k == 0 {
            ModInt(1, M)
        } else {
            dp[k - 1][0] + dp[k - 1][1]
        };
    }

    put!(dp[n-1][0] + dp[n-1][1]);

}

#[derive(Debug, PartialEq, Eq, Clone, Copy)]
struct ModInt(i64, i64);  // (residual, modulo)
impl ModInt {
    fn new(residual: i64, modulo: i64) -> ModInt {
        if residual >= modulo { ModInt(residual % modulo, modulo) }
        else if residual < 0 { ModInt((residual % modulo) + modulo, modulo) }
        else { ModInt(residual, modulo) }
    }
    fn unwrap(self) -> i64 { self.0 }
    fn inv(self) -> Self {
        fn exgcd(r0: i64, a0: i64, b0: i64, r: i64, a: i64, b: i64)
                -> (i64, i64, i64) {
            if r > 0 {
                exgcd(r, a, b, r0 % r, a0 - r0 / r * a, b0 - r0 / r * b)
            } else {
                (a0, b0, r0)
            }
        }
        let (a, _, r) = exgcd(self.0, 1, 0, self.1, 0, 1);
        if r != 1 { panic!("{:?} has no inverse!", self); }
        ModInt(((a % self.1) + self.1) % self.1, self.1)
    }
    fn pow(self, n: i64) -> Self {
        if n < 0 {
            self.pow(-n).inv()
        } else if n == 0 {
            ModInt(1, self.1)
        } else if n == 1 {
            self
        } else {
            let mut x = (self * self).pow(n / 2);
            if n % 2 == 1 { x *= self }
            x
        }
    }
}
impl std::fmt::Display for ModInt {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}
impl std::ops::Neg for ModInt {
    type Output = Self;
    fn neg(self) -> Self {
        if self.0 == 0 { return self }
        ModInt(self.1 - self.0, self.1)
    }
}
impl std::ops::Add<i64> for ModInt {
    type Output = Self;
    fn add(self, other: i64) -> Self { ModInt::new(self.0 + other, self.1) }
}
impl std::ops::Add for ModInt {
    type Output = Self;
    fn add(self, other: ModInt) -> Self { self + other.0 }
}
impl std::ops::Add<ModInt> for i64 {
    type Output = ModInt;
    fn add(self, other: ModInt) -> ModInt { other + self }
}
impl std::ops::AddAssign<i64> for ModInt {
    fn add_assign(&mut self, other: i64) { self.0 = ModInt::new(self.0 + other, self.1).0; }
}
impl std::ops::AddAssign for ModInt {
    fn add_assign(&mut self, other: ModInt) { *self += other.0; }
}
impl std::ops::Sub<i64> for ModInt {
    type Output = Self;
    fn sub(self, other: i64) -> Self { ModInt::new(self.0 - other, self.1) }
}
impl std::ops::Sub for ModInt {
    type Output = Self;
    fn sub(self, other: ModInt) -> Self { self - other.0 }
}
impl std::ops::Sub<ModInt> for i64 {
    type Output = ModInt;
    fn sub(self, other: ModInt) -> ModInt { ModInt::new(self - other.0, other.1) }
}
impl std::ops::SubAssign<i64> for ModInt {
    fn sub_assign(&mut self, other: i64) { self.0 = ModInt::new(self.0 - other, self.1).0; }
}
impl std::ops::SubAssign for ModInt {
    fn sub_assign(&mut self, other: ModInt) { *self -= other.0; }
}
impl std::ops::Mul<i64> for ModInt {
    type Output = Self;
    fn mul(self, other: i64) -> Self { ModInt::new(self.0 * other, self.1) }
}
impl std::ops::Mul for ModInt {
    type Output = Self;
    fn mul(self, other: ModInt) -> Self { self * other.0 }
}
impl std::ops::Mul<ModInt> for i64 {
    type Output = ModInt;
    fn mul(self, other: ModInt) -> ModInt { other * self }
}
impl std::ops::MulAssign<i64> for ModInt {
    fn mul_assign(&mut self, other: i64) { self.0 = ModInt::new(self.0 * other, self.1).0; }
}
impl std::ops::MulAssign for ModInt {
    fn mul_assign(&mut self, other: ModInt) { *self *= other.0; }
}
impl std::ops::Div for ModInt {
    type Output = Self;
    fn div(self, other: ModInt) -> Self { self * other.inv() }
}
impl std::ops::Div<i64> for ModInt {
    type Output = Self;
    fn div(self, other: i64) -> Self { self / ModInt(other, self.1) }
}
impl std::ops::Div<ModInt> for i64 {
    type Output = ModInt;
    fn div(self, other: ModInt) -> ModInt { other.inv() * self }
}
impl std::ops::DivAssign for ModInt {
    fn div_assign(&mut self, other: ModInt) { self.0 = (self.clone() / other).0; }
}
impl std::ops::DivAssign<i64> for ModInt {
    fn div_assign(&mut self, other: i64) { *self /= ModInt(other, self.1); }
}

trait Monoid: std::ops::Mul<Output=Self> + Clone + Copy {
    fn unit() -> Self;
}
impl Monoid for i64 { fn unit() -> Self { 0 }}
impl Monoid for f64 { fn unit() -> Self { 0.0 }}

#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
enum MinInt { Val(usize), Maximal }
impl MinInt { fn unwrap(self) -> usize { if let MinInt::Val(x) = self { x } else { panic!(); } } }
impl std::ops::Mul for MinInt {
    type Output = Self;
    fn mul(self, other: Self) -> Self {
        if self < other { self } else { other }
    }
}
impl Monoid for MinInt {
    fn unit() -> Self { MinInt::Maximal }
}

#[derive(Clone)]
struct SegmentTree<T> { size: usize, depth: usize, data: Vec<Vec<T>> }
impl<T> std::ops::Index<usize> for SegmentTree<T> {
    type Output = T;
    fn index(&self, i: usize) -> &Self::Output {
        &self.data[self.depth - 1][i]
    }
}
impl<T: Monoid> SegmentTree<T> {
    fn new(size: usize) -> SegmentTree<T> {
        let mut data = vec![];
        let mut i = 1;
        loop {
            data.push(vec![T::unit(); i]);
            if i >= size { break }
            i *= 2;
        }
        SegmentTree { size: size, depth: data.len(), data: data }
    }
    fn to_vec(self) -> Vec<T> {
        (self.data[self.depth - 1][0..self.size]).to_vec()
    }
    fn update(&mut self, idx: usize, t: T) {
        self.data[self.depth - 1][idx] = t;
        let mut i = idx;
        for d in (0..self.depth - 1).rev() {
            i /= 2;
            self.data[d][i] = self.data[d + 1][i * 2] * self.data[d + 1][i * 2 + 1];
        }
    }
    fn product(&self, range: std::ops::Range<usize>) -> T {
        if range.end == 0 || range.start + 1 > range.end {
            T::unit()
        } else if range.start + 1 == range.end {
            self[range.start]
        } else {
            let mut i = range.start;
            let mut d = self.depth - 1;
            let mut width = 1;
            while d > 0 {
                let left = (i / 2) * width * 2;
                let right = left + width * 2;
                if left == range.start && right <= range.end {
                    i /= 2;
                    d -= 1;
                    width *= 2;
                } else {
                    break
                }
            }
            let right = range.start + width;
            self.data[d][i] * self.product(right..range.end)
        }
    }
}
impl<T: std::fmt::Debug> SegmentTree<T> {
    fn debug(&self) {
        for i in 0..self.depth {
            trace!(&self.data[i]);
        }
    }
}

use std::io::{self, Write};
use std::str::FromStr;
use std::collections::VecDeque;

struct Scanner { stdin: io::Stdin, buffer: VecDeque<String>, }
impl Scanner {
    fn new() -> Self { Scanner { stdin: io::stdin(), buffer: VecDeque::new() } }
    fn cin<T: FromStr>(&mut self) -> T {
        while self.buffer.len() == 0 {
            let mut line = String::new();
            let _ = self.stdin.read_line(&mut line);
            for w in line.split_whitespace() {
                self.buffer.push_back(String::from(w));
            }
        }
        self.buffer.pop_front().unwrap().parse::<T>().ok().unwrap()
    }
    fn chars(&mut self) -> Vec<char> { self.cin::<String>().chars().collect() }
    fn vec<T: FromStr>(&mut self, n: usize) -> Vec<T> { (0..n).map(|_| self.cin()).collect() }
}


Measured memory_bytes: 28924