#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define fi first
#define se second
typedef pair<ll,ll> P;
using VP = vector<P>; using VVP = vector<VP>;
using VI = vector<ll>; using VVI = vector<VI>; using VVVI = vector<VVI>;
const int inf=1e9+7;
const ll INF=1LL<<61;
const ll mod=998244353;

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< 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 i,j;
  int n;
  cin>>n;
  vector<P> v;
  for(i=0;i<n;i++){
    ll x,d;
    cin>>x>>d;
    v.pb(P(x,d));
  }
  sort(v.begin(),v.end());
  vector<P> w;
  for(i=0;i<n;i++){
    w.pb(P(v[i].fi,i));
    w.pb(P(v[i].fi+v[i].se,-i-1));
  }
  sort(w.begin(),w.end());
  stack<int> st;
  vector<int> r(n);
  vector<int> range(n);
  SegmentTree< int > seg(n, [](int a, int b) { return max(a, b); }, 0);
  for(i=2*n-1;i>=0;i--){
    if(w[i].se<0){
      int u=-w[i].se-1;
      st.push(u);
    }
    else{
      int p=w[i].se;
      while(st.size()){
        int u=st.top();
        st.pop();
        r[u]=p;
      }
      range[p]=seg.query(p,r[p]+1);
      chmax(range[p],r[p]);
      seg.update(p,range[p]);
    }
  }
  //for(i=0;i<n;i++) cout<<i<<" "<<range[i]<<endl;
  VI ans(n+1,0);
  ans[n]=1;
  for(i=n-1;i>=0;i--){
    ans[i]=ans[i+1]+ans[range[i]+1];
    ans[i]%=mod;
    //cout<<i<<" "<<ans[i]<<endl;
  }
  cout<<ans[0]<<endl;
}

Measured memory_bytes: 17512