#include <bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
using Int = long long;
const char newl = '\n';


template<typename ...Ts>
decltype(auto) zip(vector<Ts>... args){
  vector<decltype(make_tuple(args[0]...))> res;
  int n=min({args.size()...});
  res.reserve(n);
  for(int i=0;i<n;i++) res.emplace_back(args[i]...);
  return res;
}


template<typename T,T MOD = 1000000007>
struct Mint{
  static constexpr T mod = MOD;
  T v;
  Mint():v(0){}
  Mint(signed v):v(v){}
  Mint(long long t){v=t%MOD;if(v<0) v+=MOD;}

  Mint pow(long long k){
    Mint res(1),tmp(v);
    while(k){
      if(k&1) res*=tmp;
      tmp*=tmp;
      k>>=1;
    }
    return res;
  }

  static Mint add_identity(){return Mint(0);}
  static Mint mul_identity(){return Mint(1);}

  Mint inv(){return pow(MOD-2);}

  Mint& operator+=(Mint a){v+=a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator-=(Mint a){v+=MOD-a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator*=(Mint a){v=1LL*v*a.v%MOD;return *this;}
  Mint& operator/=(Mint a){return (*this)*=a.inv();}

  Mint operator+(Mint a) const{return Mint(v)+=a;}
  Mint operator-(Mint a) const{return Mint(v)-=a;}
  Mint operator*(Mint a) const{return Mint(v)*=a;}
  Mint operator/(Mint a) const{return Mint(v)/=a;}

  Mint operator-() const{return v?Mint(MOD-v):Mint(v);}

  bool operator==(const Mint a)const{return v==a.v;}
  bool operator!=(const Mint a)const{return v!=a.v;}
  bool operator <(const Mint a)const{return v <a.v;}

  static Mint comb(long long n,int k){
    Mint num(1),dom(1);
    for(int i=0;i<k;i++){
      num*=Mint(n-i);
      dom*=Mint(i+1);
    }
    return num/dom;
  }
};
template<typename T,T MOD> constexpr T Mint<T, MOD>::mod;
template<typename T,T MOD>
ostream& operator<<(ostream &os,Mint<T, MOD> m){os<<m.v;return os;}


template <typename T>
struct SegmentTree{
  using F = function<T(T,T)>;
  int n;
  F f;
  T ti;
  vector<T> dat;

  SegmentTree(){}
  SegmentTree(F f,T ti):f(f),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 set_val(int k,T x){
    dat[k+=n]=x;
    while(k>>=1)
      dat[k]=f(dat[(k<<1)|0],dat[(k<<1)|1]);
  }

  T query(int a,int b){
    if(a>=b) return ti;
    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);
  }

  template<typename C>
  int find(int st,C &check,T &acc,int k,int l,int r){
    if(l+1==r){
      acc=f(acc,dat[k]);
      return check(acc)?k-n:-1;
    }
    int m=(l+r)>>1;
    if(m<=st) return find(st,check,acc,(k<<1)|1,m,r);
    if(st<=l&&!check(f(acc,dat[k]))){
      acc=f(acc,dat[k]);
      return -1;
    }
    int vl=find(st,check,acc,(k<<1)|0,l,m);
    if(~vl) return vl;
    return find(st,check,acc,(k<<1)|1,m,r);
  }

  template<typename C>
  int find(int st,C &check){
    T acc=ti;
    return find(st,check,acc,1,0,n);
  }
};

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  int n;
  cin>>n;
  vector<int> xs(n),ds(n);
  for(int i=0;i<n;i++) cin>>xs[i]>>ds[i];

  auto vp=zip(xs,ds);
  sort(vp.begin(),vp.end());
  for(int i=0;i<n;i++) tie(xs[i],ds[i])=vp[i];

  vector<int> nx(n);
  for(int i=0;i<n;i++)
    nx[i]=lower_bound(xs.begin(),xs.end(),xs[i]+ds[i])-xs.begin();

  auto f=[&](int a,int b){return max(a,b);};
  SegmentTree<int> seg(f,0);
  seg.build(nx);
  for(int i=n-1;i>=0;i--){
    nx[i]=seg.query(i,nx[i]);
    seg.set_val(i,nx[i]);
  }

  using M = Mint<int, 998244353>;
  vector<M> dp(n+1,M(0));
  dp[n]=M(1);
  for(int i=n-1;i>=0;i--) dp[i]=dp[i+1]+dp[nx[i]];

  cout<<dp[0]<<newl;
  return 0;
}


Measured memory_bytes: 7008