#include<bits/stdc++.h>
using namespace std;

template <int MOD_> struct modnum {
	static constexpr int MOD = MOD_;
	static_assert(MOD_ > 0, "MOD must be positive");

private:
	using ll = long long;

	int v;

	static int minv(int a, int m) {
		a %= m;
		assert(a);
		return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
	}

public:

	modnum() : v(0) {}
	modnum(ll v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
	explicit operator int() const { return v; }
	friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
	friend std::istream& operator >> (std::istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }

	friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
	friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }

	modnum inv() const {
		modnum res;
		res.v = minv(v, MOD);
		return res;
	}
	friend modnum inv(const modnum& m) { return m.inv(); }
	modnum neg() const {
		modnum res;
		res.v = v ? MOD-v : 0;
		return res;
	}
	friend modnum neg(const modnum& m) { return m.neg(); }

	modnum operator- () const {
		return neg();
	}
	modnum operator+ () const {
		return modnum(*this);
	}

	modnum& operator ++ () {
		v ++;
		if (v == MOD) v = 0;
		return *this;
	}
	modnum& operator -- () {
		if (v == 0) v = MOD;
		v --;
		return *this;
	}
	modnum& operator += (const modnum& o) {
		v += o.v;
		if (v >= MOD) v -= MOD;
		return *this;
	}
	modnum& operator -= (const modnum& o) {
		v -= o.v;
		if (v < 0) v += MOD;
		return *this;
	}
	modnum& operator *= (const modnum& o) {
		v = int(ll(v) * ll(o.v) % MOD);
		return *this;
	}
	modnum& operator /= (const modnum& o) {
		return *this *= o.inv();
	}

	friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
	friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
	friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
	friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
	friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
	friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};
using num = modnum<998244353>;

int main() {
	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	int N; cin >> N;
	vector<pair<int, int>> robots(N);
	for (auto& it : robots) { cin >> it.first >> it.second; it.second += it.first; }

	sort(robots.begin(), robots.end());

	for (auto& it : robots) {
		it.second = int(lower_bound(robots.begin(), robots.end(), pair<int, int>(it.second, -2e9)) - robots.begin());
	}

	const int S = 1 << 18;
	vector<int> seg(2*S);

	vector<num> dp(N+1);
	dp[N] = 1;
	for (int i = N-1; i >= 0; i--) {
		assert(robots[i].second > i);
		int furthest = robots[i].second;
		for (int a = S+i+1, b = S+robots[i].second; a < b; a /= 2, b /= 2) {
			if (a & 1) furthest = max(furthest, seg[a++]);
			if (b & 1) furthest = max(furthest, seg[--b]);
		}
		seg[S+i] = furthest;
		for (int a = (S+i)/2; a; a /= 2) {
			seg[a] = max(seg[2*a], seg[2*a+1]);
		}

		dp[i] = dp[i+1] + dp[furthest];
	}
	cout << dp[0] << '\n';

	return 0;
}


Measured memory_bytes: 4608