#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template<class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i,a,n) for(int (i)=(a);(i)<(n);++(i))
#define eFOR(i,a,n) for(int (i)=(a);(i)<=(n);++(i))
#define rFOR(i,a,n) for(int (i)=(n)-1;(i)>=(a);--(i))
#define erFOR(i,a,n) for(int (i)=(n);(i)>=(a);--(i))
#define each(i, a) for(auto &i : a)
#define SORT(i) sort((i).begin(),(i).end())
#define rSORT(i,a) sort((i).begin(),(i).end(),(a))
#define all(i) (i).begin(),(i).end()
#define out(y,x) ((y) < 0 || h <= (y) || (x) < 0 || w <= (x))
#define line cout << "-----------------------------\n" 
#define ENDL(i,n) ((i) == (n) - 1 ? "\n" : " ")
#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
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; }
inline void init() { cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); }
template<class T>inline istream& operator>>(istream& is, vector<T>& v) { for (auto& elemnt : v)is >> elemnt; return is; }
template<class T>inline istream& operator>>(istream& is, deque<T>& v) { for (auto& elemnt : v)is >> elemnt; return is; }
template<class T, class U>inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template<class T>inline vector<T> vec(size_t a) { return vector<T>(a); }
template<class T>inline vector<T> defvec(T def, size_t a) { return vector<T>(a, def); }
template<class T, class... Ts>inline auto vec(size_t a, Ts... ts) { return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template<class T, class... Ts>inline auto defvec(T def, size_t a, Ts... ts) { return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }

template<class T> class segtree {
	using F1 = function<T(T, T)>;
	using F2 = function<void(T&, T)>;
	T unit;
	F1 f1;
	F2 f2;

	int n = 1;
	vector<T> dat;
public:
	segtree() {}
	segtree(const int& _n, const F1& _f1, const F2& _f2, const T _unit = 0)
		: f1(_f1), f2(_f2), unit(_unit) {
		while (n < _n)n <<= 1;
		dat.resize(n << 1, unit);
	}
	segtree(const vector<T>& _dat, const F1& _f1, const F2& _f2, const T _unit = 0)
		: f1(_f1), f2(_f2), unit(_unit) {
		int _n = _dat.size();
		while (n < _n)n <<= 1;
		dat.resize(n << 1, unit);
		FOR(i, 0, _n)dat[i + n] = _dat[i];
		rFOR(i, 1, n)dat[i] = f1(dat[i << 1], dat[i << 1 | 1]);
	}
	void update(int i, T a) {
		i += n;
		f2(dat[i], a);
		while (1 < i) {
			i >>= 1;
			dat[i] = f1(dat[i << 1], dat[i << 1 | 1]);
		}
	}
	T value(int l, int r) {
		T ret = unit;
		for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
			if (l & 1)ret = f1(ret, dat[l++]);
			if (r & 1)ret = f1(ret, dat[--r]);
		}
		return ret;
	}
	T operator[](int i) { return dat[i + n]; }
};

int main() {
    init();

	int n; cin >> n;
	vector<pair<int, int>> xd(n); cin >> xd;
    SORT(xd);

	segtree<int> arr(VI(n, -1),
		[](int a, int b) {return max(a, b); },
		[](int& a, int b) {a = b; }, -1);
	arr.update(n - 1, n);
	rFOR(i, 0, n - 1) {
		int reach = xd[i].first + xd[i].second;
		int l = i, r = n;
		while (r - l > 1) {
			int mid = l + r >> 1;
			if (xd[mid].first < reach)l = mid;
			else r = mid;
		}
		if (l == i)arr.update(i, i + 1);
		else arr.update(i, arr.value(i + 1, r));
	}

    VL dp(n + 1);
    dp[0] = 1;
    FOR(i, 0, n) {
        dp[i + 1] = (dp[i] + dp[i + 1]) % MOD;
		int to = arr[i];
        dp[to] = (dp[i] + dp[to]) % MOD;
    }

    cout << dp[n] << "\n";
}

Measured memory_bytes: 5488