// template version 1.15
using namespace std;
#include <bits/stdc++.h>

// varibable settings
#define int long long
const int INF=1e18;

// define basic macro {{{
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define _rrep(i,n) rrepi(i,0,n)
#define rrepi(i,a,b) for(int i=(int)((b)-1);i>=(int)(a);--i)
#define rrep(...) _overload3(__VA_ARGS__,rrepi,_rrep,)(__VA_ARGS__)
#define each(i,a) for (auto&& i : a)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(a, b, c) make_tuple(a, b, c)
#define ub upper_bound
#define lb lower_bound
#define posl(A, x) (lower_bound(all(A), x)-A.begin())
#define posu(A, x) (upper_bound(all(A),x)-A.begin())
template<class T> inline void chmax(T &a, const T &b) { if((a) < (b)) (a) = (b); }
template<class T> inline void chmin(T &a, const T &b) { if((a) > (b)) (a) = (b); }

#define divceil(a,b) ((a)+(b)-1)/(b)
#define is_in(x, a, b) ((a)<=(x) && (x)<(b))
#define uni(x) sort(all(x));x.erase(unique(all(x)),x.end())
#define slice(l, r) substr(l, r-l)

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef long double ld;
typedef pair<int,int> pii;
typedef tuple<int,int,int> iii;

template<typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
struct Fast { Fast(){ std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

#if defined(PCM) || defined(LOCAL)
    #include "lib/dump.hpp"
#else
    #define dump(...) 42
    #define dump_1d(...) 42
    #define dump_2d(...) 42
    #define cerrendl 42
#endif
//}}}

int mod = 998244353;
struct mint { //{{{
    int x;
    mint(int x=0):x((x%mod+mod)%mod){}

    // ?= operator
    mint& operator+=(const mint a) { (x += a.x) %= mod; return *this; }
    mint& operator-=(const mint a) { (x += mod-a.x) %= mod; return *this; }
    mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this; }
    mint&operator/=(const mint&rhs){return *this*=rhs.inv();}

    mint operator+(const mint a) const { mint res(*this); return res+=a; }
    mint operator-(const mint a) const { mint res(*this); return res-=a; }
    mint operator*(const mint a) const { mint res(*this); return res*=a; }
    mint operator/(const mint&rhs)const{return mint(*this)/=rhs;}

    mint pow(int n)const{
        mint res(1),x(*this);
        if (n<0){
            n = -n;
            x =(*this).inv();
        }
        while(n){
            if(n&1)res*=x;
            x*=x;
            n>>=1;
        }
        return res;
    }
    mint inv()const{return pow(mod-2);}
    /*mint inv()const{
      int x,y;
      int g=extgcd(v,mod,x,y);
      assert(g==1);
      if(x<0)x+=mod;
      return mint(x);
      }*/
    friend ostream& operator<<(ostream&os,const mint&m){
        return os<<m.x;
    }
    bool operator<(const mint&r)const{return x<r.x;}
    bool operator==(const mint&r)const{return x==r.x;}
};
//}}}


template<typename T>
struct SegmentTree { // {{{
    private:
        using F = function<T(T,T)>;
        int n;  // 元の配列のサイズ
        int N;  // n以上の最小の2冪
        vector<T> node;
        F merge;
        T identity;

    public:
        SegmentTree(vector<T> a, F f, T id):merge(f), identity(id) {
            n = a.size();
            N = 1; while(N < n) N *= 2;
            node.resize(2*N-1, identity);
            for(int i=0; i<n; i++) node[i+N-1] = a[i];
            for(int i=N-2; i>=0; i--) node[i] = merge(node[2*i+1], node[2*i+2]);
        }
        SegmentTree(int n, F f, T id) : SegmentTree(vector<T>(n, id), f, id) {}

        T& operator[](int i) { return node[i+N-1]; }

        void update(int x, T val) {
            x += (N - 1);
            node[x] = val;
            while(x > 0) {
                x = (x - 1) / 2;
                node[x] = merge(node[2*x+1], node[2*x+2]);
            }
        }

        void add(int x, T val) {
            x += (N - 1);
            node[x] += val;
            while(x > 0) {
                x = (x - 1) / 2;
                node[x] = merge(node[2*x+1], node[2*x+2]);
            }
        }

        // query for [l, r)
        T query(int a, int b, int k=0, int l=0, int r=-1) {
            if(r < 0) r = N;
            if(r <= a || b <= l) return identity;
            if(a <= l && r <= b) return node[k];

            T vl = query(a, b, 2*k+1, l, (l+r)/2);
            T vr = query(a, b, 2*k+2, (l+r)/2, r);
            return merge(vl, vr);
        }

        friend ostream& operator<<(ostream &os, SegmentTree<T>& sg){ //
            os << "[";
            for(int i=0; i<sg.n; i++){
                os << sg[i] << (i==sg.n-1?"]\n":", ");
            }
            return os;
        }
};
// }}}
// Sample:
// -----------------------------------------------
// auto mymin=[](auto a, auto b){return min(a,b);};
// SegmentTree<int> seg(a, mymin, 1e18);


// -----------------------------------------------

signed main() {
    int n;cin>>n;

    vi x(n), d(n);
    vector<pii> xd(n);
    rep(i, n){
        cin>>xd[i].first>>xd[i].second;
    }
    sort(all(xd));

    rep(i, n){
        x[i] = xd[i].first;
        d[i] = xd[i].second;
    }
    dump(x);
    dump(d);

    vi dp(n);
    dp[n-1] = n-1;

    auto mymax=[](auto a, auto b){return max(a,b);};
    SegmentTree<int> seg2(vi(n, -INF), mymax, -1e18);
    seg2.update(n-1, n-1);
    rrep(i, n-1){
        if (x[i]+d[i]>x[n-1]) dp[i] = n-1;
        else{
            int j = lb(all(x), x[i]+d[i]) - x.begin();
            dump(i, j);
            dump(seg2.query(i+1, j));
            dp[i] = max(i, seg2.query(i+1, j));
        }
        seg2.update(i, dp[i]);
    }
    dump(dp);

    mint ans = 1;

    auto add=[](auto a, auto b){return a+b;};
    SegmentTree<mint> seg(vector<mint>(n+1), add, 0);
    seg.add(0, 1);
    rep(i, 1, n+1){
        int v = seg.query(0, i).x;
        dump(i, v, dp[i-1]);
        seg.add(dp[i-1]+1, v);
        dump(seg);
        ans += v;
    }
    cout << ans << endl;

    return 0;
}


Measured memory_bytes: 19940