#include "bits/stdc++.h"
using namespace std;
#define int long long
#define REP(i,n) for(int i = 0;i < (int)(n);++i)
#define RREP(i,n) for(int i = (int)n-1;i >= 0;--i)
#define FOR(i,s,n) for(int i = s;i < (int)n;++i)
#define RFOR(i,s,n) for(int i = (int)n-1;i >= s;--i)
#define ALL(a) a.begin(),a.end()
#define IN(a, x, b) (a<=x && x<b)
template<class T>inline void out(T t){cout<<t<<"\n";}
template<class T,class... Ts>inline void out(T t,Ts... ts){cout<<t<<" ";out(ts...);}
template<class T>inline bool CHMAX(T&a,T b){if(a<b){a = b;return true;}return false;}
template<class T>inline bool CHMIN(T&a,T b){if(a>b){a = b;return true;}return false;}
constexpr int INF = 1e18;

template<int MOD> struct Fp {
	long long val;
	constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
		if (val < 0) val += MOD;
	}
	constexpr int getmod() { return MOD; }
	constexpr Fp operator - () const noexcept {
		return val ? MOD - val : 0;
	}
	constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
	constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
	constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
	constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
	constexpr Fp& operator += (const Fp& r) noexcept {
		val += r.val;
		if (val >= MOD) val -= MOD;
		return *this;
	}
	constexpr Fp& operator -= (const Fp& r) noexcept {
		val -= r.val;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr Fp& operator *= (const Fp& r) noexcept {
		val = val * r.val % MOD;
		return *this;
	}
	constexpr Fp& operator /= (const Fp& r) noexcept {
		long long a = r.val, b = MOD, u = 1, v = 0;
		while (b) {
			long long t = a / b;
			a -= t * b; swap(a, b);
			u -= t * v; swap(u, v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	constexpr bool operator == (const Fp& r) const noexcept {
		return this->val == r.val;
	}
	constexpr bool operator != (const Fp& r) const noexcept {
		return this->val != r.val;
	}
	friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
		return os << x.val;
	}
	friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
		if (n == 0) return 1;
		auto t = modpow(a, n / 2);
		t = t * t;
		if (n & 1) t = t * a;
		return t;
	}
};
 
// 二項係数ライブラリ
template<class T> struct BiCoef {
	vector<T> fact_, inv_, finv_;
	constexpr BiCoef() {}
	constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) {
		init(n);
	}
	constexpr void init(int n) noexcept {
		fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1);
		int MOD = fact_[0].getmod();
		for(int i = 2; i < n; i++){
			fact_[i] = fact_[i-1] * i;
			inv_[i] = -inv_[MOD%i] * (MOD/i);
			finv_[i] = finv_[i-1] * inv_[i];
		}
	}
	constexpr T com(int n, int k) const noexcept {
		if (n < k || n < 0 || k < 0) return 0;
		return fact_[n] * finv_[k] * finv_[n-k];
	}
	constexpr T fact(int n) const noexcept {
		if (n < 0) return 0;
		return fact_[n];
	}
	constexpr T inv(int n) const noexcept {
		if (n < 0) return 0;
		return inv_[n];
	}
	constexpr T finv(int n) const noexcept {
		if (n < 0) return 0;
		return finv_[n];
	}
};
 
const int MOD = 998244353;
// const int MOD = 
using mint = Fp<MOD>;
BiCoef<mint> bc;
// bc.init(500050);
 
template <typename T>
struct SegmentTree{
	using F = function<T(T,T)>;
	int n;
	F f;
	T ti;
	vector<T> dat;
	SegmentTree(){};
	SegmentTree(F f,T ti):f(f),ti(ti){}
	void init(int n_){
		n=1;
		while(n<n_) n<<=1;
		dat.assign(n<<1,ti);
	}
	void build(const vector<T> &v){
		int n_=v.size();
		init(n_);
		for(int i=0;i<n_;i++) dat[n+i]=v[i];
		for(int i=n-1;i;i--)
			dat[i]=f(dat[(i<<1)|0],dat[(i<<1)|1]);
	}
	void set_val(int k,T x){
		dat[k+=n]=x;
		while(k>>=1)
			dat[k]=f(dat[(k<<1)|0],dat[(k<<1)|1]);
	}
	T query(int a,int b){
		T vl=ti,vr=ti;
		for(int l=a+n,r=b+n;l<r;l>>=1,r>>=1) {
			if(l&1) vl=f(vl,dat[l++]);
			if(r&1) vr=f(dat[--r],vr);
		}
		return f(vl,vr);
	}
};
//auto f = [](){};
//auto seg = SegmentTree<T,decltype(f)>(f,Ti);

signed main(){
	int N;
	cin >> N;
	vector<pair<int,int>>v(N);
	REP(i,N){
		cin >> v[i].first >> v[i].second;
	}
	sort(ALL(v));
	vector<int>x(N),d(N);
	vector<int>a(N);
	REP(i,N){
		x[i] = v[i].first;
		d[i] = v[i].second;
	}
	d.push_back(INF);
	auto seg = SegmentTree<int>([](int a,int b){return max(a,b);},0);
	seg.build(vector<int>(N));
	RREP(i,N){
		a[i] = upper_bound(ALL(x),x[i] + d[i] - 1) - x.begin();
		seg.set_val(i,a[i]);
		seg.set_val(i,seg.query(i,a[i]));
	}
	vector<mint>dp(N+1);
	dp[0] = 1;
	REP(i,N){
		dp[seg.query(i,i+1)] += dp[i];
		dp[i+1] += dp[i];
	}
	out(dp[N]);
}

Measured memory_bytes: 15204