#pragma GCC target("avx")
#pragma GCC optimize("O3")
  #ifndef _GLIBCXX_NO_ASSERT
  #include <cassert>
  #endif
  #include <cctype>
  #include <cerrno>
  #include <cfloat>
  #include <ciso646>
  #include <climits>
  #include <clocale>
  #include <cmath>
  #include <csetjmp>
  #include <csignal>
  #include <cstdarg>
  #include <cstddef>
  #include <cstdio>
  #include <cstdlib>
  #include <cstring>
  #include <ctime>

  #if __cplusplus >= 201103L
  #include <ccomplex>
  #include <cfenv>
  #include <cinttypes>
  #include <cstdbool>
  #include <cstdint>
  #include <ctgmath>
  #include <cwchar>
  #include <cwctype>
  #endif

  // C++
  #include <algorithm>
  #include <bitset>
  #include <complex>
  #include <deque>
  #include <exception>
  #include <fstream>
  #include <functional>
  #include <iomanip>
  #include <ios>
  #include <iosfwd>
  #include <iostream>
  #include <istream>
  #include <iterator>
  #include <limits>
  #include <list>
  #include <locale>
  #include <map>
  #include <memory>
  #include <new>
  #include <numeric>
  #include <ostream>
  #include <queue>
  #include <set>
  #include <sstream>
  #include <stack>
  #include <stdexcept>
  #include <streambuf>
  #include <string>
  #include <typeinfo>
  #include <utility>
  #include <valarray>
  #include <vector>

  #if __cplusplus >= 201103L
  #include <array>
  #include <atomic>
  #include <chrono>
  #include <condition_variable>
  #include <forward_list>
  #include <future>
  #include <initializer_list>
  #include <mutex>
  #include <random>
  #include <ratio>
  #include <regex>
  #include <scoped_allocator>
  #include <system_error>
  #include <thread>
  #include <tuple>
  #include <typeindex>
  #include <type_traits>
  #include <unordered_map>
  #include <unordered_set>
  #endif

using namespace std;

using i64 = long long;

const long long MOD = 1000000007;
const i64 INF = i64(1e18) + 7;


template <typename T>
bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

template <typename T>
bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}


template<typename T>
struct Segtree{
    int n;
    T op;
    vector<T> elm;
    function<T(T, T)> f;

    Segtree(int n, T init, function<T(T, T)> f, T op = T()) :
        n(n),
        op(op),
        elm(2 * n, init),
        f(f)
    {
        for(int i = n - 1; i >= 1; --i)
            elm[i] = f(elm[2 * i], elm[2 * i + 1]);
    }

    Segtree(int n, vector<T> init, function<T(T, T)> f, T op = T()) :
        n(n),
        op(op),
        elm(2 * n),
        f(f)
    {
        for(int i = 0; i < n; ++i)
            elm[i + n] = init[i];
        for(int i = n - 1; i >= 1; --i)
            elm[i] = f(elm[2 * i], elm[2 * i + 1]);
    }

    void set(int x, T val){
        x += n;
        elm[x] = val;
        while(x >>= 1)
            elm[x] = f(elm[2 * x], elm[2 * x + 1]);
    }

    void update(int x, T val){
        x += n;
        elm[x] = f(elm[x], val);
        while(x >>= 1)
            elm[x] = f(elm[2 * x], elm[2 * x + 1]);
    }

    T get(int x, int y) const{
        T l = op, r = op;
        for(x += n, y += n - 1; x <= y; x >>= 1, y >>= 1){
            if(x & 1)
                l = f(l, elm[x++]);
            if(!(y & 1))
                r = f(elm[y--], r);
        }
        return f(l, r);
    }
};


template <i64 mod = MOD>
struct ModInt{
    i64 p;

    ModInt() : p(0){}
    ModInt(i64 x){p = x >= 0 ? x % mod : x + (-x + mod - 1) / mod * mod;}

    ModInt& operator+=(const ModInt& y){p = p + *y - ((p + *y) >= mod ? mod : 0); return *this;}
    ModInt& operator-=(const ModInt& y){p = p - *y + (p - *y < 0 ? mod : 0); return *this;}
    ModInt& operator*=(const ModInt& y){p = (p * *y) % mod; return *this;}
    ModInt& operator%=(const ModInt& y){if(y)p %= *y; return *this;}

    ModInt operator+(const ModInt& y) const{ModInt x = *this; return x += y;}
    ModInt operator-(const ModInt& y) const{ModInt x = *this; return x -= y;}
    ModInt operator*(const ModInt& y) const{ModInt x = *this; return x *= y;}
    ModInt operator%(const ModInt& y) const{ModInt x = *this; return x %= y;}

    friend ostream& operator<<(ostream& stream, const ModInt<mod>& x){
        stream << *x;
        return stream;
    }

    friend ostream& operator>>(ostream& stream, const ModInt<mod>& x){
        stream >> *x;
        return stream;
    }

    ModInt& operator++(){p = (p + 1) % mod; return *this;}
    ModInt& operator--(){p = (p - 1 + mod) % mod; return *this;}

    bool operator==(const ModInt& y) const{return p == *y;}
    bool operator!=(const ModInt& y) const{return p != *y;}

    const i64& operator*() const{return p;}
    i64& operator*(){return p;}

};

using mint = ModInt<998244353>;



int main(){
    int n;
    cin	>> n;
    vector<int> x(n), d(n);
    vector<pair<int,int>> v;
    for(int i = 0; i < n; ++i){
        cin	>> x[i] >> d[i];
        v.emplace_back(x[i], d[i]);
    }
    sort(v.begin(), v.end());
    for(int i = 0; i < n; ++i){
        x[i] = v[i].first;
        d[i] = v[i].first + v[i].second;
    }
    Segtree<int> seg(n, d, [](auto x, auto y){return max(x, y);}, -MOD);
    for(int i = n - 2; i >= 0; --i){
        int r = distance(x.begin(), lower_bound(x.begin(), x.end(), d[i]));
        seg.update(i, seg.get(i, r));
    }

    vector<int> idxes(n);
    for(int i = 0; i < n; ++i)
        idxes[i] = distance(x.begin(), lower_bound(x.begin(), x.end(), seg.get(i, i + 1)));

    mint ans = 0;
    vector<mint> dp(n + 1);
    dp[0] = 1;
    for(int i = 0; i < n; ++i){
        ans += dp[i];
        dp[idxes[i]] += ans;
    }
    cout << accumulate(dp.begin(), dp.end(), mint(0)) << endl;

}



Measured memory_bytes: 7280