#include <iostream>
#include <sstream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <memory>
#include <complex>
#include <numeric>
#include <cstdio>
#include <iomanip>
#include <random>

#define REP(i,m,n) for(int i=int(m);i<int(n);i++)
#define RREP(i,m,n) for(int i=int(n)-1;i>=int(m);--i)
#define EACH(i,c) for (auto &(i): c)
#define all(c) begin(c),end(c)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(begin(c),end(c))
#define pb emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
//#define int long long

#ifdef LOCAL
#define DEBUG(s) cout << (s) << endl
#define dump(x)  cerr << #x << " = " << (x) << endl
#define BR cout << endl;
#else
#define DEBUG(s) do{}while(0)
#define dump(x) do{}while(0)
#define BR 
#endif
using namespace std;

using UI = unsigned int;
using UL = unsigned long;
using LL = long long;
using ULL = unsigned long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VLL = vector<LL>;
using VVLL = vector<VLL>;
using VS = vector<string>;
using PII = pair<int,int>;
using VP = vector<PII>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

constexpr int MOD = 998244353;

// auto mod int
struct mint {
    LL x;
    mint(LL x=0):x((x%MOD+MOD)%MOD){}
    mint operator-() const { return mint(-x);}
    mint& operator+=(const mint a) {
        if ((x += a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator-=(const mint a) {
        if ((x += MOD-a.x) >= MOD) x -= MOD;
        return *this;
    }
    mint& operator*=(const mint a) {
        (x *= a.x) %= MOD;
        return *this;
    }
    mint operator+(const mint a) const {
        mint res(*this);
        return res+=a;
    }
    mint operator-(const mint a) const {
        mint res(*this);
        return res-=a;
    }
    mint operator*(const mint a) const {
        mint res(*this);
        return res*=a;
    }
    mint pow(const LL &t) const {
        if (!t) return 1;
        mint a = pow(t>>1);
        a *= a;
        if (t&1) a *= *this;
        return a;
    }

    // for prime MOD
    mint inv() const {
        return pow(MOD-2);
    }
    mint& operator/=(const mint a) {
        return (*this) *= a.inv();
    }
    mint operator/(const mint a) const {
        mint res(*this);
        return res/=a;
    }
    LL operator()() const {
        return x;
    }
};
using VM = vector<mint>;
using VVM = vector<VM>;

struct S {
    int x,d;
};

template<typename T = long long>
class SegmentTree {
public:
    std::vector<T> ary;
    int n;
    const T default_value = -1 * (1 << 30);
    SegmentTree(int n) {
        this->n = 1;
        while (this->n < n) this->n *= 2;
        ary.resize(this->n * 2 - 1, default_value); // sum -> 0, min -> INF, 0?
    }
    T ope(T l, T r) {
        return std::max(l, r);
    }
    void update(int k, T d) {
        k += n - 1;
        ary[k] = d;
        while (k > 0) {
            k = (k - 1) / 2;
            ary[k] = ope(ary[2 * k + 1], ary[2 * k + 2]);
        }
    }
    T query(int a, int b) {
        return query(a, b, 0, n, 0);
    }
    T query(int a, int b, int l, int r, int i) {
        if (a <= l && b >= r) return ary[i];
        //if (a >= r || b <= l) return 0; // sum
        if (a >= r || b <= l) return default_value; // min
        int m = (l + r) / 2;
        T vl = query(a, b, l, m, 2 * i + 1);
        T vr = query(a, b, m, r, 2 * i + 2);
        return ope(vl, vr);
    }
};

void solve() {
    int n;
    cin >> n;

    vector<S> ss(n);
    REP(i,0,n) cin >> ss[i].x >> ss[i].d;
    sort(all(ss), [](auto &l, auto &r) {return l.x < r.x;});

    SegmentTree<int> sg(n);
    REP(i,0,n) sg.update(i,ss[i].x + ss[i].d);

    vector<mint> dp(n), ru(n+1);
    ru[n] = 1;
    RREP(i,0,n) {
        S tmps;
        tmps.x = ss[i].x + ss[i].d - 1;

        int prevd = -1, d;
        auto it = upper_bound(all(ss), tmps, [](auto &l, auto &r) {return l.x < r.x;});
        prevd = distance(ss.begin(), it);
        //if (i == 0) dump(prevd);
        for (;;) {
            int mv = sg.query(i, prevd);
            //if (i == 0) dump(mv);
            tmps.x = mv - 1;        
            auto it = upper_bound(all(ss), tmps, [](auto &l, auto &r) {return l.x < r.x;});
            d = distance(ss.begin(), it);
            if (d == prevd) break;
            prevd = d;
        }
        sg.update(i, max(ss[prevd].x, ss[i].x + ss[i].d));

        dp[i] = ru[d];
        ru[i] = ru[i+1] + dp[i];
    }
    cout << ru[0]() << endl;

    return;

    REP(i,0,n) {
        cout << dp[i]() << " ";
    }
    cout << endl;
    REP(i,0,n+1) {
        cout << ru[i]() << " ";
    }
    cout << endl;
}

signed main() {
    solve();
    
    return 0;
}

Measured memory_bytes: 7040