#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <functional>
#include <bitset>

using namespace std;
using lint = long long int;
long long int INF = 1001001001001001LL;
int inf = 1000000007;
long long int MOD = 998244353;
double PI = 3.1415926535897932;

template<typename T1,typename T2>inline void chmin(T1 &a,const T2 &b){if(a>b) a=b;}
template<typename T1,typename T2>inline void chmax(T1 &a,const T2 &b){if(a<b) a=b;}

#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()

/* do your best */

// quoted from beet-aizu
template <typename T, typename E, typename F, typename G>
struct SegmentTree{
    // using F = function<T(T, T)>
    // using G = function<T(T, E)>
    int n;
    F f;
    G g;
    T ti;
    vector<T> dat;
    SegmentTree(){};
    SegmentTree(F f,G g,T ti):f(f),g(g),ti(ti){}
    void init(int n_){    
        n=1;
        while(n<n_) n<<=1;
        dat.assign(n<<1,ti);
    }
    void build(const vector<T> &v){
        int n_=v.size();
        init(n_);
        for(int i=0;i<n_;i++) dat[n+i]=v[i];
        for(int i=n-1;i;i--)
            dat[i]=f(dat[(i<<1)|0],dat[(i<<1)|1]);
    }
    void update(int k,const E &x){
        k += n;
        dat[k] = g(dat[k], x);
        while(k>>=1)
            dat[k]=f(dat[(k<<1)|0],dat[(k<<1)|1]);    
    }
    T operator [](int k) const { return dat[k+n]; }
    T query(int a,int b) const {
        T vl=ti,vr=ti;
        for(int l=a+n,r=b+n;l<r;l>>=1,r>>=1) {
            if(l&1) vl=f(vl,dat[l++]);
            if(r&1) vr=f(dat[--r],vr);
        }
        return f(vl,vr);
    }

    /* TODO わからない 聞く 
    template<typename C>
    int find(int a,int b,C &check,int k,int l,int r){
        if(!check(dat[k])||r<=a||b<=l) return -1;
        if(k>=n) return k-n;
        int m=(l+r)>>1;
        int vl=find(a,b,check,(k<<1)|0,l,m);
        if(~vl) return vl;
        return find(a,b,check,(k<<1)|1,m,r);
    }
    template<typename C>
    int find(int a,int b,C &check){
        return find(a,b,check,1,0,n);
    }*/
    
};


int main() {
  
  lint n; cin >> n;
  vector<lint> x(n);
  vector<lint> d(n);
  vector<pair<lint, lint>> pi(n);
  for(int i = 0; i < n; i++) {
    cin >> x[i] >> d[i];
    pi[i] = {x[i], d[i]};
  }

  sort(ALL(pi));
  for(int i = 0; i < n; i++) {
    x[i] = pi[i].first;
    d[i] = pi[i].second;
  }

  vector<lint> dp(n + 1, 0);
  dp[0] = 1LL;
  vector<lint> sup(n); // i を取ると次は sup[i] からは取れなくなる
  for(int i = 0; i < n; i++) {
    lint l = i;
    lint r = n;
    lint goal = x[i] + d[i];
    if(i == n - 1) {
      sup[i] = n - 1;
    }
    while(r - l > 1) {
      lint mi = (r + l) / 2;
      lint mx = x[mi];
      if(goal <= mx) {
        r = mi;
      } else {
        l = mi;
      }
      sup[i] = l;
    }
  }
  /*
  for(int i = 0; i < n; i++) {
    cerr << "x[i] = " << x[i] << ", d[i] = " << d[i] << endl;
  }
  */

  using T = lint;  // type T
  using E = lint;  // type E
  auto f = [](T a, T b){ // return type T value
    return max(a, b);
  };
  auto g = [](T a, E b){ // return type T value
    return b;  // return b;
  };
  T ti = 0;  // identify element
  SegmentTree<T, E, decltype(f), decltype(g)> sg(f, g, ti);  // don't change
  sg.build(sup);   // 初期配列を代入
  for(int i = 0; i < n; i++) {
    lint ma = sg.query(i, sup[i] + 1);
    sg.update(i, ma);
  }
  for(int i = n - 1; i >= 0; i--) {
    lint ma = sg.query(i, sup[i] + 1);
    sg.update(i, ma);
  }
  for(int i = 0; i < n; i++) 
    sup[i] = sg.query(i, i + 1);

  // for debug

  for(int i = 0; i < n; i++) {
    if(dp[i] == 0) continue;
    // 取らない
    dp[i + 1] += dp[i];
    dp[i + 1] %= MOD;

    // 取る
    dp[sup[i] + 1] += dp[i];
    dp[sup[i] + 1] %= MOD;
  }

  cout << dp[n] << endl;
  return 0;
}



Measured memory_bytes: 13696