#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <tuple>
#include <cassert>

using namespace std;

#define all(c) (c).begin(), (c).end()
#define iter(c) __typeof((c).begin())
#define cpresent(c, e) (find(all(c), (e)) != (c).end())
#define tr(c, i) for (iter(c) i = (c).begin(); i != (c).end(); ++i)
#define pb(e) push_back(e)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define mp(a,b) make_pair((a), (b))
#define mt(a,b,c) make_tuple((a),(b),(c))
#define MOD 998244353
typedef long long ll;

template< typename Monoid >
struct SegmentTree {
  using F = function< Monoid(Monoid, Monoid) >;

  int sz;
  vector< Monoid > seg;

  const F f;
  const Monoid M1;

  SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1) {
    sz = 1;
    while(sz < n) sz <<= 1;
    seg.assign(2 * sz, M1);
  }

  void set(int k, const Monoid &x) {
    seg[k + sz] = x;
  }

  void build() {
    for(int k = sz - 1; k > 0; k--) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  void update(int k, const Monoid &x) {
    k += sz;
    seg[k] = x;
    while(k >>= 1) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  Monoid query(int a, int b) {
    Monoid L = M1, R = M1;
    for(a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if(a & 1) L = f(L, seg[a++]);
      if(b & 1) R = f(seg[--b], R);
    }
    return f(L, R);
  }

  Monoid operator[](const int &k) const {
    return seg[k + sz];
  }

  template< typename C >
  int find_subtree(int a, const C &check, Monoid &M, bool type) {
    while(a < sz) {
      Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]);
      if(check(nxt)) a = 2 * a + type;
      else M = nxt, a = 2 * a + 1 - type;
    }
    return a - sz;
  }


  template< typename C >
  int find_first(int a, const C &check) {
    Monoid L = M1;
    if(a <= 0) {
      if(check(f(L, seg[1]))) return find_subtree(1, check, L, false);
      return -1;
    }
    int b = sz;
    for(a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if(a & 1) {
        Monoid nxt = f(L, seg[a]);
        if(check(nxt)) return find_subtree(a, check, L, false);
        L = nxt;
        ++a;
      }
    }
    return -1;
  }

  template< typename C >
  int find_last(int b, const C &check) {
    Monoid R = M1;
    if(b >= sz) {
      if(check(f(seg[1], R))) return find_subtree(1, check, R, true);
      return -1;
    }
    int a = sz;
    for(b += sz; a < b; a >>= 1, b >>= 1) {
      if(b & 1) {
        Monoid nxt = f(seg[--b], R);
        if(check(nxt)) return find_subtree(b, check, R, true);
        R = nxt;
      }
    }
    return -1;
  }
};


int main(){
    int n; cin >> n;
    vector<int> x(n),d(n);
    rep(i,n) cin >> x[i] >> d[i];
    vector<pair<int,int>> vp(n);
    rep(i,n){vp[i].first = x[i]; vp[i].second = i;}
    sort(all(vp));
    vector<ll> dp(n+1);
    SegmentTree< int > seg(n, [](int a, int b) {return max(a, b);}, -1);
  //  rep(i,n) cout << vp[i].first << " " << d[vp[i].second] << endl;
    dp[n] = 1;
    vector<int> to(n);
    for(int i=n-1;i>=0;i--){
        int ind = vp[i].second;
        int xx = x[ind], dd = d[ind];
        int id = lower_bound(all(vp), make_pair(xx+dd, -1)) - vp.begin();
        to[i] = id;
        int cm = seg.query(i,to[i]);
        seg.update(i, max(to[i], cm));
        to[i] = max(to[i], cm);
       // cout << to[i] << endl;
    }
    for(int i=n-1;i>=0;i--){
        if(to[i] >= n) dp[i] = (dp[i+1] + 1) % MOD;
        else dp[i] = (dp[i+1] + dp[to[i]]) % MOD;
    //    cout << dp[i] << endl;
    }
    cout << dp[0] << endl;
    return 0;
}

Measured memory_bytes: 7808