#include <bits/stdc++.h>  // clang-format off
using namespace std;
using Int = long long;
#define REP_(i, a_, b_, a, b, ...) for (int i = (a), lim_i = (b); i < lim_i; i++)
#define REP(i, ...) REP_((i), __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
struct SetupIO { SetupIO() { cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(13); } } setup_io;
#ifndef _MY_DEBUG
#define dump(...)
#endif  // clang-format on

/**
 *    author:  knshnb
 *    created: Sat Mar  7 21:00:02 JST 2020
 **/

template <class T> T pow(T x, int n, const T UNION = 1) {
    T ret = UNION;
    while (n) {
        if (n & 1) ret *= x;
        x *= x;
        n >>= 1;
    }
    return ret;
}

template <int MD> struct ModInt {
    int x;
    static unordered_map<int, int> to_inv;
    ModInt() : x(0) {}
    ModInt(long long x_) {
        if ((x = x_ % MD + MD) >= MD) x -= MD;
    }

    ModInt& operator+=(ModInt that) {
        if ((x += that.x) >= MD) x -= MD;
        return *this;
    }
    ModInt& operator*=(ModInt that) {
        x = (unsigned long long)x * that.x % MD;
        return *this;
    }
    ModInt& operator-=(ModInt that) {
        if ((x -= that.x) < 0) x += MD;
        return *this;
    }
    ModInt& operator/=(ModInt that) {
        x = (unsigned long long)x * that.inv().x % MD;
        return *this;
    }
    ModInt operator-() const { return -x < 0 ? MD - x : -x; }
    ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
    ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
    ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
    ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }
    bool operator==(ModInt that) const { return x == that.x; }
    bool operator!=(ModInt that) const { return x != that.x; }
    ModInt inv() const { return to_inv.count(this->x) ? to_inv[this->x] : (to_inv[this->x] = pow(*this, MD - 2).x); }

    friend ostream& operator<<(ostream& s, ModInt<MD> a) {
        s << a.x;
        return s;
    }
    friend istream& operator>>(istream& s, ModInt<MD>& a) {
        long long tmp;
        s >> tmp;
        a = ModInt<MD>(tmp);
        return s;
    }
    friend string to_string(ModInt<MD> a) { return to_string(a.x); }
};
template <int MD> unordered_map<int, int> ModInt<MD>::to_inv;
using mint = ModInt<998244353>;

vector<mint> fact, fact_inv;
void init_factorial(int n) {
    fact = vector<mint>(n + 1, 1);
    fact_inv = vector<mint>(n + 1);
    for (int i = 0; i < n; i++) fact[i + 1] = fact[i] * (i + 1);
    fact_inv[n] = mint(1) / fact[n];
    for (int i = n - 1; i >= 0; i--) fact_inv[i] = fact_inv[i + 1] * (i + 1);
    // for (int i = 0; i < n + 1; i++) assert(fact[i] * fact_inv[i] == 1);
}
mint comb(int n, int r) { return fact[n] * fact_inv[r] * fact_inv[n - r]; }

using pii = pair<Int, Int>;
const Int INF = 1e15;
signed main() {
    Int n;
    cin >> n;
    vector<pii> ps(n);
    REP(i, n) {
        Int x, d;
        cin >> x >> d;
        ps[i] = {x, x + d};
    }
    sort(ps.begin(), ps.end());
    vector<mint> dp(n + 1, 1);
    map<Int, Int> mp;
    mp[INF] = n;
    for (Int i = n - 1; i >= 0; i--) {
        Int idx = i;
        while (mp.begin()->first < ps[i].second) {
            idx = mp.begin()->second;
            mp.erase(mp.begin());
        }
        mp[ps[i].first] = idx;
        dp[i] = dp[i + 1] + dp[idx + 1];
    }
    cout << dp[0] << endl;
}


Measured memory_bytes: 10496