#include <map>
#include <set>
#include <vector>
#include <algorithm>
#include <iostream>
#include <bitset>
#include <cassert>
#include <queue>
#include <random>
#include <stack>
#include <iomanip>
#include <functional>

using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

template <class A, class B>
string to_string(pair<A, B> p);

template <class A, class B, class C>
string to_string(tuple<A, B, C> p);

template <class A, class B, class C, class D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s) {
    return '"' + s + '"';
}

string to_string(const char* s) {
    return to_string((string) s);
}

string to_string(bool b) {
    return (b ? "true" : "false");
}

string to_string(vector<bool> v) {
    bool first = true;
    string res = "{";
    for (int i = 0; i < static_cast<int>(v.size()); i++) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(v[i]);
    }
    res += "}";
    return res;
}

template <size_t N>
string to_string(bitset<N> v) {
    string res = "";
    for (size_t i = 0; i < N; i++) {
        res += static_cast<char>('0' + v[i]);
    }
    return res;
}

template <class A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for (const auto &x : v) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}

template <class A, class B>
string to_string(pair<A, B> p) {
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <class A, class B, class C>
string to_string(tuple<A, B, C> p) {
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <class A, class B, class C, class D>
string to_string(tuple<A, B, C, D> p) {
    return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << endl; }

template <class Head, class... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

using Int = unsigned int;
using llong = long long;
using Llong = unsigned long long;
using ldouble = long double;
using intV = vector<int>;
using llongV = vector<long long>;
using llongVV = vector<vector<long long>>;

template<class T = int>
using asc_pque = priority_queue<T, vector<T>, greater<T>>;
template<class T = int>
using desc_pque = priority_queue<T, vector<T>, less<T>>;

const llong MOD = 998244353LL;
const int IINF = 1000000000;
const llong LINF = 100000000000000000LL;

#define FOR(i, n) for (llong i = 0LL; i < llong(n); i++)
#define FORS(i, a, b) for (llong i = llong(a); i < llong(b); i++)
#define sup(vec, a) upper_bound(vec.begin(), vec.end(), a) - vec.begin()
#define inf(vec, a) lower_bound(vec.begin(), vec.end(), a) - vec.begin()
#define GET(i, T) get<i>(T)

set<llong> V;
llongV R;
llong cnt = 0;

llong dfs(llong i) {
    if(V.find(i) == V.end()) return 0;
    V.erase(i);

    llong ret = 1;
    for(auto to = V.lower_bound(i + 1); to != V.end();){
        llong v = *to;
        if(v >= R[i]) break;
        ret = (ret * (dfs(v) + 1)) % MOD;
        to = V.lower_bound(v + 1);
    }
    return ret;
}

int main(void) {
    cin.tie(0);
    ios::sync_with_stdio(false);

    llong N;
    cin >> N;

    vector<pair<llong, llong>> XD(N);

    FOR(i, N) {
        cin >> XD[i].first >> XD[i].second;
        V.insert(i);
    }

    sort(XD.begin(), XD.end());

    llongV X(N);
    R = llongV(N);
    FOR(i, N) {
        X[i] = XD[i].first;
    }

    FOR(i, N) {
        llong x, d;
        tie(x, d) = XD[i];
        R[i] = lower_bound(X.begin(), X.end(), x + d) - X.begin();
    }

    llong ans = 1;
    FOR(i, N) {
        if(V.find(i) == V.end()) continue;
        llong prd = 1;
        FORS(to, i + 1, R[i]) {
            if(V.find(to) != V.end()) {
                prd = (prd * (dfs(to) + 1)) % MOD;
            }
        }
        ans = (ans * (prd + 1)) % MOD;
        V.erase(i);
    }

    cout << ans << endl;
    debug(V);

    return 0;
}

Measured memory_bytes: 25216