#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <iomanip>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <cstdint>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
#define MP make_pair
#define PB push_back
#define inf 1000000007
#define rep(i,n) for(int i = 0; i < (int)(n); ++i)
#define all(x) (x).begin(),(x).end()

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
    std::fill( (T*)array, (T*)(array+N), val );
}
 
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;
}

template <unsigned int mod>
class ModInt {
private:
    unsigned int v;
    static unsigned int norm(const unsigned int& x){ return x < mod ? x : x - mod; }
    static ModInt make(const unsigned int& x){ ModInt m; return m.v = x, m; }
    static ModInt inv(const ModInt& x){ return make(inverse(x.v, mod)); }
    static unsigned int inverse(int a, int m){
        int u[] = {a, 1, 0}, v[] = {m, 0, 1}, t;
        while(*v){
            t = *u / *v;
            swap(u[0] -= t * v[0], v[0]), swap(u[1] -= t * v[1], v[1]), swap(u[2] -= t * v[2], v[2]);
        }
        return (u[1] % m + m) % m;
    }

public:
    ModInt() : v{0}{}
    ModInt(const long long val) : v{norm(val % mod + mod)} {}
    ModInt(const ModInt<mod>& n) : v{n()} {}
    explicit operator bool() const noexcept { return v != 0; }
    bool operator!() const noexcept { return !static_cast<bool>(*this); }
    ModInt& operator=(const ModInt& n){ return v = n(), (*this); }
    ModInt& operator=(const long long val){ return v = norm(val % mod + mod), (*this); }
    ModInt operator+() const { return *this; }
    ModInt operator-() const { return v == 0 ? make(0) : make(mod - v); }
    ModInt operator+(const ModInt& val) const { return make(norm(v + val())); }
    ModInt operator-(const ModInt& val) const { return make(norm(v + mod - val())); }
    ModInt operator*(const ModInt& val) const { return make((long long)v * val() % mod); }
    ModInt operator/(const ModInt& val) const { return *this * inv(val); }
    ModInt& operator+=(const ModInt& val){ return *this = *this + val; }
    ModInt& operator-=(const ModInt& val){ return *this = *this - val; }
    ModInt& operator*=(const ModInt& val){ return *this = *this * val; }
    ModInt& operator/=(const ModInt& val){ return *this = *this / val; }
    ModInt operator+(const long long val) const { return ModInt{v + val}; }
    ModInt operator-(const long long val) const { return ModInt{v - val}; }
    ModInt operator*(const long long val) const { return ModInt{(long long)v * (val % mod)}; }
    ModInt operator/(const long long val) const { return ModInt{(long long)v * inv(val)}; }
    ModInt& operator+=(const long long val){ return *this = *this + val; }
    ModInt& operator-=(const long long val){ return *this = *this - val; }
    ModInt& operator*=(const long long val){ return *this = *this * val; }
    ModInt& operator/=(const long long val){ return *this = *this / val; }
    bool operator==(const ModInt& val) const { return v == val.v; }
    bool operator!=(const ModInt& val) const { return !(*this == val); }
    bool operator==(const long long val) const { return v == norm(val % mod + mod); }
    bool operator!=(const long long val) const { return !(*this == val); }
    unsigned int operator()() const { return v; }
    friend ModInt operator+(const long long val, const ModInt& n) { return n + val; }
    friend ModInt operator-(const long long val, const ModInt& n) { return ModInt{val - n()}; }
    friend ModInt operator*(const long long val, const ModInt& n) { return n * val; }
    friend ModInt operator/(const long long val, const ModInt& n) { return ModInt{val} / n; }
    friend bool operator==(const long long val, const ModInt& n) { return n == val; }
    friend bool operator!=(const long long val, const ModInt& n) { return !(val == n); }
    friend istream& operator>>(istream& is, ModInt& n){
        unsigned int v;
        return is >> v, n = v, is;
    }
    friend ostream& operator<<(ostream& os, const ModInt& n){ return (os << n()); }
    friend ModInt mod_pow(ModInt x, long long n){
        ModInt ans = 1;
        while(n){
            if(n & 1) ans *= x;
            x *= x, n >>= 1;
        }
        return ans;
    }
};

#define MOD 998244353
using mod = ModInt<MOD>;

template<typename T> class segtree{
private:
    int n,sz;
    vector<T> node;
public:
    segtree(const vector<T>& v) : n(1), sz((int)v.size()){
        while(n < sz) n *= 2;
        node.resize(2*n-1,0);
        for(int i = 0; i < sz; i++){
            node[i+n-1] = v[i];
        }
        for(int i=n-2; i>=0; i--){
            node[i] = node[i*2+1] + node[i*2+2];
        }
    }
    void update(int k,T a){
        k += n-1;
        node[k] = a;
        while(k>0){
            k = (k-1)/2;
            node[k] = node[2*k+1]+node[2*k+2];
        }
    }
    T query(int a,int b,int k=0,int l=0,int r=-1){
        if(r < 0) r = n;
        if(r <= a || b <= l){
            return 0;
        }
        if(a <= l && r <= b){
            return node[k];
        }else{
            T vl = query(a,b,2*k+1,l,(l+r)/2);
            T vr = query(a,b,2*k+2,(l+r)/2,r);
            return vl+vr;
        }
    }
    void print(){
        for(int i = 0; i < sz; i++){
            cout<<query(i,i+1)<< " ";
        }
        cout<<endl;
    }
};


template<typename T> class segtree2{
private:
    int n,sz;
    vector<T> node;
public:
    segtree2(const vector<T>& v) : n(1), sz((int)v.size()){
        while(n < sz) n *= 2;
        node.resize(2*n-1, numeric_limits<T>::min());
        for(int i = 0; i < sz; i++){
            node[i+n-1] = v[i];
        }
        for(int i=n-2; i>=0; i--){
            node[i] = max(node[i*2+1], node[i*2+2]);
        }
    }
    void update(int k,T a){
        k += n-1;
        node[k] = a;
        while(k>0){
            k = (k-1)/2;
            node[k] = max(node[2*k+1],node[2*k+2]);
        }
    }
    T query(int a,int b,int k=0,int l=0,int r=-1){
        if(r < 0) r = n;
        if(r <= a || b <= l){
            return numeric_limits<T>::min();
        }
        if(a <= l && r <= b){
            return node[k];
        }else{
            T vl = query(a,b,2*k+1,l,(l+r)/2);
            T vr = query(a,b,2*k+2,(l+r)/2,r);
            return max(vl,vr);
        }
    }
    void print(){
        for(int i = 0; i < sz; i++){
            cout<<query(i,i+1)<< " ";
        }
        cout<<endl;
    }
};


int main(){
    int n;
    cin >> n;
    vector<pair<int,int> >a(n);
    rep(i,n){
        int x,d;
        cin >> x >> d;
        a[i] = MP(x,d);
    }
    sort(all(a));
    int mx = -inf;
    int cnt = 0;
    vector<mod> v(n+1);
    segtree<mod> sg(v);
    
    vector<int> p(n);
    segtree2<int> sg2(p);
    
    sg.update(n,1);
    
    rep(i,n){
        p[i] = lower_bound(all(a),MP(a[i].first+a[i].second,-inf))-a.begin();
        sg2.update(i,p[i]);
    }
    for(int i=n-1;i>=0;i--){
        int k = sg2.query(i,p[i]);
        sg2.update(i,k);
    }
    for(int i=n-1;i>=0;i--){
        mod res = sg.query(sg2.query(i,i+1),sg2.query(i,i+1)+1) + sg.query(i+1,i+2);
        sg.update(i,res);
    }
    cout << sg.query(0,1) << endl;
    return 0;
}

Measured memory_bytes: 7552