#pragma GCC optimize("O3")
#pragma GCC target("avx")
#pragma GCC optimize("unroll-loops")
#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define DB double
#define ST string
#define BS bitset
#define VE vector
#define VL vector<LL>
#define VP vector<pair<LL,LL>>
#define VVL vector<vector<LL>>
#define PQ priority_queue<LL>
#define PQS priority_queue<LL, vector<LL>, greater<LL>>
#define PB push_back
#define POB pop_back
#define PF push_front
#define POF pop_front
#define MP make_pair
#define TS to_string
#define TU to_ullong
#define FOR(i,a,n) for(i=a;i<n;i++)
#define rep(i,n) FOR(i,0,n)
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define SORT(a) sort(ALL(a))
#define REV(a) reverse(ALL(a))
#define UB(a,n) *upper_bound(ALL(a),n)
#define LB(a,n) *lower_bound(ALL(a),n)
#define INF 1145141919810364364
#define PI 3.14159265358979
//#define MOD 1000000007
#define MOD 998244353
#define ERR 0.00000000000001
#define NUM 200010

void Yn(LL a){if(a)printf("Yes\n");else printf("No\n");}
void YN(LL a){if(a)printf("YES\n");else printf("NO\n");}
LL pwmn(LL a,LL n){LL ans=1;while(ans<a)ans*=n;return ans;}
LL GCD(LL a,LL b){LL c=1,tmp=max(a,b);b=min(a,b);a=tmp;while(c!=0){c=a%b;a=b;b=c;}return a;}
LL LCM(LL a,LL b){return a*b/GCD(a,b);}
LL mod(LL a,LL m){if(a<0)return a%m+m;else return a%m;}
LL DIV(LL a,LL d){LL m=MOD,x=1,y=0,k;while(m){k=d/m;d-=k*m;swap(m,d);x-=k*y;swap(x,y);}return mod(a*mod(x,MOD),MOD);}
LL FAC(LL a){LL i,ans=1;FOR(i,1,a+1){ans*=i;if(MOD>0&&ans>MOD)ans%=MOD;}return ans;}
LL POW(LL a,LL n){LL ans=1;while(n>0){if(n&1)ans=ans*a%MOD;a=a*a%MOD;n>>=1;}return ans;}
LL fact[NUM],finv[NUM],inv[NUM];
void comi(){LL i;fact[0]=fact[1]=1;finv[0]=finv[1]=1;inv[1]=1;FOR(i,2,NUM){fact[i]=fact[i-1]*i%MOD;inv[i]=MOD-inv[MOD%i]*(MOD/i)%MOD;finv[i]=finv[i-1]*inv[i]%MOD;}}
LL com(LL n,LL k){if(n<k||n<0||k<0)return 0;return fact[n]*(finv[k]*finv[n-k]%MOD)%MOD;}
template<typename T>bool chmax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<typename T>bool chmin(T &a,T b){if(a>b){a=b;return true;}return false;}

struct Seg{
private:
  LL st;
  VL node;
public:
  Seg(LL n){
    st=pwmn(n,2);
    node.resize(2*st-1);
  }
  Seg(VL v){
    LL i;
    st=pwmn(v.size(),2);
    node.resize(2*st-1);
    rep(i,v.size())node[i+st-1]=v[i];
    for(i=st-2;i>=0;i--)node[i]=max(node[2*i+1],node[2*i+2]);
  }
  void sadd(LL i,LL n){
    i+=st-1;
    node[i]=n;
    while(i>0){
      i=(i-1)/2;
      node[i]=max(node[2*i+1],node[2*i+2]);
    }
  }
  LL smax(LL a,LL b,LL k=0,LL l=0,LL r=-1){
    if(r<0)r=st;
    if(r<=a||b<=l)return 0;
    if(a<=l&&r<=b)return node[k];
    return max(smax(a,b,2*k+1,l,(l+r)/2),smax(a,b,2*k+2,(l+r)/2,r));
  }
};

LL up(VP &v,LL n){
  LL mx=v.size(),mn=0,md;
  while(mx-mn>1){
    md=(mx+mn)/2;
    if(v[md].first>=n)mx=md;
    else mn=md;
  }
  return mn;
}

int main(){
  LL i,a=0,ans=0,N;
  cin>>N;
  VL v(N),dp(N);
  VP p(N);
  rep(i,N)cin>>p[i].first>>p[i].second;
  SORT(p);
  Seg s(N);
  for(i=N-1;i>=0;i--){
    a=s.smax(i+1,up(p,p[i].first+p[i].second)+1);
    s.sadd(i,max(i,a));
  }
  rep(i,N)v[i]=s.smax(i,i+1);
  dp[N-1]=2;
  for(i=N-2;i>=0;i--){
    dp[i]+=dp[i+1];
    if(v[i]<N-1)dp[i]+=dp[v[i]+1];
    else dp[i]++;
    dp[i]%=MOD;
  }
  cout<<dp[0]<<endl;
}


Measured memory_bytes: 10624