#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (q < m) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;


constexpr lint MOD = 998244353;

// Nonrecursive Segment Tree (point-update, range-get)
// - Conditions for operations:
//   - datamerge: [TDATA, TDATA] -> TDATA, e(x, y) == e(y, x)
//   - data2ret: [TDATA, TQUERY] -> TRET
//   - retmerge: [TRET, TRET] -> TRET, g(defaultRET, x) == x, g(x, y) = g(y, x)
//   - commutability f(e(x, y), q) == g(f(x, q), f(y, q))
template<typename TDATA, typename TRET, typename TQUERY>
struct NonrecursiveSegmentTree
{
    int N;
    TRET defaultRET;
    virtual TDATA datamerge(const TDATA &, const TDATA &) = 0;
    virtual TRET data2ret(const TDATA &, const TQUERY &) = 0;
    virtual TRET retmerge(const TRET &, const TRET &) = 0;
    std::vector<TDATA> data;
    inline TDATA& at(int i) { return data[i]; }

    inline void _merge(int i) { at(i) = datamerge(at(i << 1), at((i << 1) + 1)); }
    void initialize(const std::vector<TDATA> &seq, TRET RET_ZERO) {
        N = seq.size();
        defaultRET = RET_ZERO;
        data = seq;
        data.insert(data.end(), seq.begin(), seq.end());
        for (int i = N - 1; i; i--) _merge(i);
    }
    NonrecursiveSegmentTree() = default;
    void update(int pos, const TDATA &x) {
        assert(pos >= 0 and pos < N);
        at(pos + N) = x;
        for (int i = pos + N; i > 1;) i >>= 1, _merge(i);
    }

    // [l, r), 0-indexed
    TRET get(int l, int r, TQUERY query = NULL) {
        assert(l >= 0 and r <= N);
        TRET retl = defaultRET, retr = defaultRET;
        l += N, r += N;
        while (l < r) {
            if (l & 1) retl = retmerge(retl, data2ret(data[l++], query));
            if (r & 1) retr = retmerge(data2ret(data[--r], query), retr);
            l >>= 1, r >>= 1;
        }
        return retmerge(retl, retr);
    }

    template<typename T1, typename T2, typename T3>
    friend std::ostream &operator<<(std::ostream &os, NonrecursiveSegmentTree<T1, T2, T3> s) {
        os << "[SegmentTree (len: " << s.N << ')';
        for (int i = 0; i < s.N; i++) os << s.at(i + s.N) << ',';
        os << "]";
        return os;
    }
};


// Range Maximum Query
// - get: return min(x_l, ..., x_{r - 1})
template <typename T>
struct RangeMaximumQuery : public NonrecursiveSegmentTree<T, T, bool>
{
    using SegTree = NonrecursiveSegmentTree<T, T, bool>;
    T datamerge(const T &vl, const T &vr) override { return std::max(vl, vr); };
    T data2ret(const T &v, const bool &q) override { return v; }
    T retmerge(const T &vl, const T &vr) override { return std::max(vl, vr); };
    RangeMaximumQuery(const std::vector<T> &seq, T defaultmax) : SegTree::NonrecursiveSegmentTree() {
        SegTree::initialize(seq, defaultmax);
    };
};


template <int mod>
struct ModInt
{
    using lint = long long;
    static int get_mod() { return mod; }
    static int get_primitive_root() {
        static int primitive_root = 0;
        if (!primitive_root) {
            primitive_root = [&](){
                std::set<int> fac;
                int v = mod - 1;
                for (lint i = 2; i * i <= v; i++) while (v % i == 0) fac.insert(i), v /= i;
                if (v > 1) fac.insert(v);
                for (int g = 1; g < mod; g++) {
                    bool ok = true;
                    for (auto i : fac) if (ModInt(g).power((mod - 1) / i) == 1) { ok = false; break; }
                    if (ok) return g;
                }
                return -1;
            }();
        }
        return primitive_root;
    }
    int val;
    constexpr ModInt() : val(0) {}
    constexpr ModInt &_setval(lint v) { val = (v >= mod ? v - mod : v); return *this; }
    constexpr ModInt(lint v) { _setval(v % mod + mod); }
    explicit operator bool() const { return val != 0; }
    constexpr ModInt operator+(const ModInt &x) const { return ModInt()._setval((lint)val + x.val); }
    constexpr ModInt operator-(const ModInt &x) const { return ModInt()._setval((lint)val - x.val + mod); }
    constexpr ModInt operator*(const ModInt &x) const { return ModInt()._setval((lint)val * x.val % mod); }
    constexpr ModInt operator/(const ModInt &x) const { return ModInt()._setval((lint)val * x.inv() % mod); }
    constexpr ModInt operator-() const { return ModInt()._setval(mod - val); }
    constexpr ModInt &operator+=(const ModInt &x) { return *this = *this + x; }
    constexpr ModInt &operator-=(const ModInt &x) { return *this = *this - x; }
    constexpr ModInt &operator*=(const ModInt &x) { return *this = *this * x; }
    constexpr ModInt &operator/=(const ModInt &x) { return *this = *this / x; }
    friend constexpr ModInt operator+(lint a, const ModInt &x) { return ModInt()._setval(a % mod + x.val); }
    friend constexpr ModInt operator-(lint a, const ModInt &x) { return ModInt()._setval(a % mod - x.val + mod); }
    friend constexpr ModInt operator*(lint a, const ModInt &x) { return ModInt()._setval(a % mod * x.val % mod); }
    friend constexpr ModInt operator/(lint a, const ModInt &x) { return ModInt()._setval(a % mod * x.inv() % mod); }
    constexpr bool operator==(const ModInt &x) const { return val == x.val; }
    constexpr bool operator!=(const ModInt &x) const { return val != x.val; }
    bool operator<(const ModInt &x) const { return val < x.val; }  // To use std::map<ModInt, T>
    friend std::istream &operator>>(std::istream &is, ModInt &x) { lint t; is >> t; x = ModInt(t); return is; }
    friend std::ostream &operator<<(std::ostream &os, const ModInt &x) { os << x.val;  return os; }
    constexpr lint power(lint n) const {
        lint ans = 1, tmp = this->val;
        while (n) {
            if (n & 1) ans = ans * tmp % mod;
            tmp = tmp * tmp % mod;
            n /= 2;
        }
        return ans;
    }
    constexpr lint inv() const { return this->power(mod - 2); }
    constexpr ModInt operator^(lint n) const { return ModInt(this->power(n)); }
    constexpr ModInt &operator^=(lint n) { return *this = *this ^ n; }

    inline ModInt fac() const {
        static std::vector<ModInt> facs;
        int l0 = facs.size();
        if (l0 > this->val) return facs[this->val];

        facs.resize(this->val + 1);
        for (int i = l0; i <= this->val; i++) facs[i] = (i == 0 ? ModInt(1) : facs[i - 1] * ModInt(i));
        return facs[this->val];
    }

    ModInt doublefac() const {
        lint k = (this->val + 1) / 2;
        if (this->val & 1) return ModInt(k * 2).fac() / ModInt(2).power(k) / ModInt(k).fac();
        else return ModInt(k).fac() * ModInt(2).power(k);
    }

    ModInt nCr(const ModInt &r) const {
        if (this->val < r.val) return ModInt(0);
        return this->fac() / ((*this - r).fac() * r.fac());
    }

    ModInt sqrt() const {
        if (val == 0) return 0;
        if (mod == 2) return val;
        if (power((mod - 1) / 2) != 1) return 0;
        ModInt b = 1;
        while (b.power((mod - 1) / 2) == 1) b += 1;
        int e = 0, m = mod - 1;
        while (m % 2 == 0) m >>= 1, e++;
        ModInt x = power((m - 1) / 2), y = (*this) * x * x;
        x *= (*this);
        ModInt z = b.power(m);
        while (y != 1) {
            int j = 0;
            ModInt t = y;
            while (t != 1) j++, t *= t;
            z = z.power(1LL << (e - j - 1));
            x *= z, z *= z, y *= z;
            e = j;
        }
        return ModInt(std::min(x.val, mod - x.val));
    }
};

using mint = ModInt<MOD>;
int main()
{
    int N;
    cin >> N;
    vector<pint> XD(N);
    REP(i, N) cin >> XD[i].first >> XD[i].second;
    sort(ALL(XD));
    vector<int> x2d(N);
    REP(i, N) x2d[i] = XD[i].first + XD[i].second;
    RangeMaximumQuery<int> rmq(x2d, -1e9);

    vector<mint> dp(N + 1);
    dp[N] = 1;
    IREP(i, N) {
        dp[i] += dp[i + 1];
        int j = upper_bound(ALL(XD), pint(XD[i].first + XD[i].second, -1e9)) - XD.begin();
        int y = rmq.get(i, j);
        rmq.update(i, y);
        j = upper_bound(ALL(XD), pint(y, -1e9)) - XD.begin();
        dp[i] += dp[j];
    }
    cout << dp[0] << endl;
}


Measured memory_bytes: 4992