#include<bits/stdc++.h>
//ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//clock_t start=clock();clock_t end=clock();cout<<(double)(end-start)/CLOCKS_PER_SEC<<endl;
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;
typedef pair<int,int> pii;
typedef pair<pii,int> ppii;
typedef pair<int,pii> pipi;
typedef pair<ll,ll> pll;
typedef pair<pll,ll> ppll;
typedef pair<ll,pll> plpl;
typedef tuple<ll,ll,ll> tl;
typedef pair<double,double> pdd;
ll mod=1000000007;
ll mod2=998244353;
ll mod3=1000003;
ll mod4=998244853;
ll mod5=1000000009;
ll inf=1LL<<60;
double pi=3.141592653589793238462643383279L;
double eps=1e-9;
#define rep(i,m,n) for(ll i=m;i<n;i++)
#define rrep(i,n,m) for(ll i=n;i>=m;i--)
#define srep(itr,st) for(auto itr=st.begin();itr!=st.end();itr++)
#define Max(a,b) a=max(a,b)
#define Min(a,b) a=min(a,b)
int dh[4]={1,-1,0,0};
int dw[4]={0,0,1,-1};
int ddh[8]={-1,-1,-1,0,0,1,1,1};
int ddw[8]={-1,0,1,-1,1,-1,0,1};
ll gcd(ll a,ll b){
    if(a<b)swap(a,b);
    if(b==0)return a;
    if(a%b==0)return b;
    return gcd(b,a%b);
}
ll Pow(ll n,ll k){
    ll ret=1;
    ll now=n;
    while(k>0){
        if(k&1)ret*=now;
        now*=now;
        k/=2;
    }
    return ret;
}
ll beki(ll n,ll k,ll md){
  ll ret=1;
  ll now=n;
  while(k>0){
    if(k%2==1){
      ret*=now;
      ret%=md;
    }
    now*=now;
    now%=md;
    k/=2;
  }
  return ret;
}
ll gyaku(ll n,ll md){
  return beki(n,md-2,md);
}
ll popcount(ll n){
    ll ret=0;
    ll u=n;
    while(u>0){
        ret+=u%2;
        u/=2;
        
    }
    return ret;
}
int main(){
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int n;cin>>n;
    vector<pll> v;
    ll x[n],d[n];
    rep(i,0,n){
        cin>>x[i]>>d[i];
        v.push_back({x[i],i});
    }
    sort(v.begin(),v.end());
    v.push_back({inf,-1});
    ll len[n];
    fill(len,len+n,-1);
    ll len2[n];
    ll now=0;
    rep(i,0,n){
        ll num=v[i].second;
        ll ri=x[num]+d[num];
        pll p={ri,-2};
        ll y=lower_bound(v.begin(),v.end(),p)-v.begin();
        y--;
        len2[i]=y;
    }
    ll par[n];
    set<ll> st;
    vector<ll> syu[n];
    rep(i,0,n){
        syu[len2[i]].push_back(i);
    }
    rep(i,0,n){
        st.insert(i);
        rep(j,0,syu[i].size()){
            st.erase(syu[i][j]);
            auto itr=st.lower_bound(syu[i][j]);
            if(itr==st.end()){
                len[syu[i][j]]=len2[syu[i][j]];
                par[syu[i][j]]=syu[i][j];
            }
            else{
                par[syu[i][j]]=*itr;
            }
        }
    }
    rrep(i,n-1,0){
        if(len[i]==-1){
            len[i]=len[par[i]];
        }
    }
    ll par2[n];
    vector<ll> la[n];
    rrep(i,n-1,0){
        la[len[i]].push_back(i);
    }
    set<ll> st2;
    vector<ll> w[n+1];
    rep(i,0,n){
        if(st2.size()==0){
            par2[i]=n;
            w[n].push_back(i);
        }
        else{
            auto itr=st2.end();itr--;
            par2[i]=*itr;
            w[*itr].push_back(i);
        }
        st2.insert(i);
        rep(j,0,la[i].size()){
            ll num=la[i][j];
            st2.erase(num);
        }
    }
    queue<ll> q;
    ll ans[n+1];
    rep(i,0,n){
        if(w[i].size()==0){
            q.push(i);
            
        }
    }
    ll cnt[n+1];
    fill(cnt,cnt+n+1,0);
    /*rep(i,0,w[2].size())cout<<w[2][i]<<" ";
    cout<<endl;*/
    while(q.size()>0){
        ll now=q.front();q.pop();
        //cout<<now<<endl;
        ans[now]=1;
        rep(i,0,w[now].size()){
            (ans[now]*=ans[w[now][i]])%=mod2;
            //cout<<now<<" "<<w[now][i]<<endl;
        }
        if(now==n)break;
        ans[now]++;
        ans[now]%=mod2;
        ll pp=par2[now];
        cnt[pp]++;
        
        if(cnt[pp]==w[pp].size())q.push(pp);
    }
    //rep(i,0,n+1)cout<<ans[i]<<" ";
    cout<<ans[n]<<endl;
}









Measured memory_bytes: 51564