#include <iostream>
#include <array>
#include <algorithm>
#include <vector>
#include <bitset>
#include <set>
#include <unordered_set>
#include <cmath>
#include <complex>
#include <deque>
#include <iterator>
#include <numeric>
#include <map>
#include <unordered_map>
#include <queue>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <limits>
#include <iomanip>
#include <functional>
#include <cassert>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define rep(i, k, n) for (ll i=k; i<(ll)n; ++i)
#define REP(i, n) rep(i, 0, n)
#define ALL(v) v.begin(),v.end()
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; }
#define DEBUG_VLL(vec) REP(sz, vec.size()) std::cerr<<vec[sz]<<(sz==vec.size()-1?'\n':' ');

const long long MOD = 998244353;
const long long HIGHINF = (long long)1e18;
const int INF = (int)1e9;

class ModInt {
public:
    long long x;
    constexpr ModInt(const long long x=0) : x((x+MOD)%MOD) {}
    constexpr ModInt& operator+=(const ModInt rhs) {
        x += rhs.x;
        if (x >= MOD) x -= MOD;
        return *this;
    }
    constexpr ModInt operator+(const ModInt rhs) const {
        return ModInt(*this) += rhs; 
    }
    constexpr ModInt& operator-=(const ModInt& rhs) {
        x -= rhs.x;
        if (x < 0) x += MOD;
        return *this;
    }
    constexpr ModInt operator-(const ModInt rhs) const {
        return ModInt(*this) -= rhs; 
    }
    constexpr ModInt& operator*=(const ModInt& rhs) {
        x = x * rhs.x % MOD;
        return *this;
    }
    constexpr ModInt operator*(const ModInt rhs) const {
        return ModInt(*this) *= rhs; 
    }
    constexpr ModInt& operator/=(const ModInt& rhs) {
        ModInt div = powmod(rhs, MOD - 2);
        (x *= div.x) %= MOD;
        return *this;
    }
    constexpr ModInt operator/(const ModInt rhs) const {
        return ModInt(*this) /= rhs;
    }
    constexpr ModInt powmod(ModInt m, long long p) {
        if (p == 0) return ModInt(1);
        ModInt tmp = powmod(m, p / 2);
        if (p & 1) return tmp * tmp * m;
        else return tmp * tmp;
    }
    constexpr ModInt& operator++() {
        x += 1;
        return *this;
    }
    constexpr ModInt operator++(int) {
        ModInt tmp(*this);
        operator++();
        return tmp;
    }
    constexpr ModInt& operator--() {
        x -= 1;
        return *this;
    }
    constexpr ModInt operator--(int) {
        ModInt tmp(*this);
        operator--();
        return tmp;
    }

    friend ostream& operator<<(ostream& os, const ModInt &rhs) {
        os << rhs.x;
        return os;
    }
    friend istream& operator>>(istream& is, ModInt& rhs) {
        is >> rhs.x;
        return is;
    }
};
bool operator==(const ModInt& lhs, const ModInt& rhs) {
    return lhs.x == rhs.x;
}
bool operator!=(const ModInt& lhs, const ModInt& rhs) {
    return !(lhs == rhs);
}
ModInt powmod(ModInt m, long long p) {
    if (p == 0) return ModInt(1);
    ModInt tmp = powmod(m, p / 2);
    if (p & 1) return tmp * tmp * m;
    else return tmp * tmp;
}

using modi = ModInt;

template < class T >
class SegmentTree {
    // 0-indexed Segment Tree
    long long n; // 葉の数
    vector<T> data;  // データを格納する配列
    T def;  // 初期値（単位元）
    function<T(T, T)> operation;  // 区間クエリで使う処理
    function<T(T, T)> update;  // 点更新で使う処理

    // 区間 [a, b) に対する query !!!!!
    T _query(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) return def;
        if (a <= l && r <= b) return data[k];  // a,l,r,bの順で含まれる
        else {
            T c1 = _query(a, b, 2*k+1, l, (l+r)>>1);
            T c2 = _query(a, b, 2*k+2, (l+r)>>1, r);
            return operation(c1, c2);
        }
    }

public:
    // _n: 葉の要素の数, _def: 初期値（単位元）, _operation: クエリの関数, _update: 更新用の関数
    SegmentTree(size_t _n, T _def, function<T(T, T)> _operation, function<T(T, T)> _update)
        : n(_n), def(_def), operation(_operation), update(_update) {
            n = 1;
            while (n < _n) n<<=1;
            data = vector<T>(2*n-1, def);
        }
    
    void change(int i, T x) {
        i += n - 1;
        data[i] = update(data[i], x);
        while (i>0) {
            i = (i-1)>>1;
            data[i] = operation(data[i*2+1], data[i*2+2]);
        }
    }

    // 区間 [a, b) に対する query !!!!!
    T query(int a, int b) {
        return _query(a, b, 0, 0, n);
    }

    T operator[](int i) {
        return data[i+n-1];
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    V< P<ll, ll> > xd(n);
    vll comx = {HIGHINF + 5};
    for (int i = 0; i < n; i++) {
        cin >> xd[i].first >> xd[i].second;
        comx.emplace_back(xd[i].first);
    }
    sort(ALL(xd));
    sort(ALL(comx));

    SegmentTree<int> seg(n + 1, -INF,
        [&](int i, int j) {return max(i, j); },
        [&](int i, int j) {return j; });
    for (int i = 0; i < n; i++) seg.change(i, i);
    seg.change(n, n - 1);
    for (int i = n - 1; i >= 0; i--) {
        int r = lower_bound(ALL(comx), xd[i].first + xd[i].second) - comx.begin();
        seg.change(i, seg.query(i, r));
    }
    
    V<modi> dp(n + 1, 0);
    dp[n] = 1;
    for (int i = n - 1; i >= 0; i--) {
        dp[i] = dp[i + 1] + dp[seg[i] + 1];
    }
    cout << dp[0] << '\n';
    return 0;
}


Measured memory_bytes: 11596