#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define repr(i, n) REPR(i, n, 0)
#define REPR(i, s, e) for(int i=(int)(s-1); i>=(int)(e); i--)
#define pb push_back
#define all(r) r.begin(),r.end()
#define rall(r) r.rbegin(),r.rend()
#define fi first
#define se second

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const ll INF = 1e18;
const ll MOD = 1e9 + 7;
const double EPS = 1e-8;

template<typename T> T chmax(T& a, const T& b){return a = (a > b ? a : b);}
template<typename T> T chmin(T& a, const T& b){return a = (a < b ? a : b);}
using ull = unsigned long long;


template <typename T, typename U> T pow_fast(T x, U n) {
    T ret = (T)1;
    while(n) {
        if(n & (U)1) ret *= x;
        x *= x;
        n >>= 1;
    }
    return ret;
}

template <typename ModType, ModType MOD> struct ModInt {
    ModType val;
    ModInt() : val(0) {}
    ModInt(ModType x) : val(x % MOD) {
        if(val < 0) val += MOD;
    };
    operator ModType() const { return val; }
    ModInt &operator+=(const ModInt &m) {
        val += m.val;
        if(val >= MOD) val -= MOD;
        return *this;
    }
    ModInt &operator-=(const ModInt &m) {
        val -= m.val;
        if(val < 0) val += MOD;
        return *this;
    }
    ModInt &operator*=(const ModInt &m) {
        (val *= m.val) %= MOD;
        return *this;
    }
    ModInt &operator/=(const ModInt &m) {
        *this *= m.inverse();
        return *this;
    }
    ModInt operator+(const ModInt &m) const { return ModInt(*this) += m; }
    ModInt operator-(const ModInt &m) const { return ModInt(*this) -= m; }
    ModInt operator*(const ModInt &m) const { return ModInt(*this) *= m; }
    ModInt operator/(const ModInt &m) const { return ModInt(*this) /= m; }
    ModInt inverse() const { return pow_fast(*this, MOD - 2); }
    ModInt pow(ModType n) const {return pow_fast(*this, n); }

    friend std::ostream &operator<<(std::ostream &os, const ModInt &rhs) {
        os << rhs.val;
        return os;
    }
    friend std::istream &operator>>(std::istream &is, ModInt &rhs) {
        ModType value;
        is >> value;
        rhs = ModInt(value);
        return is;
    }
};

constexpr ll initVal = (1LL<<31)-1;     //TODO: fix type and value
constexpr ll initLazy = (1LL<<60)-1;    //TODO: fix type and value
template <typename T>
struct Node {
    T val;
    T lazy;
    ull l, r;
    Node<T>* l_node = nullptr;
    Node<T>* r_node = nullptr;
    Node(ull l, ull r, const T& val = initVal) : l(l), r(r), val(val), lazy(initLazy) {}
    T getVal() {
        return (lazy != initLazy ? lazy : val); //TODO: fix
    }
    T f1(const T& a, const T& b) {
        return min(a, b);               //TODO: fix
    }
    T f2(const T& a, const T& b) {
        return b;                       //TODO: fix
    }
    void push() {
        if(r - l > 1) {
            auto m = (l+r)/2;
            {
                if(l_node == nullptr) l_node = new Node(l, m);
                if(lazy != initLazy) l_node->lazy = f2(l_node->lazy, this->lazy);
            }
            {
                if(r_node == nullptr) r_node = new Node(m, r);
                if(lazy != initLazy) r_node->lazy = f2(r_node->lazy, this->lazy); 
            }
        }
        val = getVal();
        lazy = initLazy;
    }
    void fix() {
        if(r - l == 1) return;
        val = f1(l_node->getVal(), r_node->getVal());
    }
    T query(ull qL, ull qR) {
        if(qR <= l || r <= qL) return initVal;
        if(qL <= l && r <= qR) return getVal();
        if(r - l == 1)  return getVal();

        push();
        T l_val = l_node->query(qL, qR), r_val = r_node->query(qL, qR);
        return f1(l_val, r_val);
    }
    void update(ull uL, ull uR, const T& uVal) {
        if(uR <= l || r <= uL) return;
        if(uL <= l && r <= uR) lazy = f2(lazy, uVal);
        else {
            push();
            l_node->update(uL, uR, uVal);
            r_node->update(uL, uR, uVal);
            fix();
        }
    }
};

template <typename T>
struct DynamicLazySegTree {
    Node<T> root;
    DynamicLazySegTree(ull l, ull r, const T& val) : root(l, r, val) {}
    T query(ull l, ull r) {
        return root.query(l, r);
    }
    void update(ull l, ull r, const T& val) {
        root.update(l, r, val);
    }
};

using mint = ModInt<ll, 998244353>;
vector<vi> es;
vector<bool> used;
mint dfs(int cur) {
    used[cur] = true;
    if(es[cur].empty()) return mint(2);
    mint ret = 1;
    for(auto&& to: es[cur]) ret *= dfs(to);
    ret += mint(1);
    return ret;
}

int main(){
    int n;
    cin >> n;
    vl x(n), d(n);
    rep(i, n) cin >> x[i] >> d[i];
    vi id(n);
    rep(i, n) id[i] = i;
    sort(all(id), [&](int a, int b) {return x[a] < x[b];});
    ll mi = INF, ma = -INF;
    rep(i, n) {
        chmin(mi, x[i]);
        chmax(ma, x[i] + d[i]);
    }
    DynamicLazySegTree<ll> st(0, ma- mi + 2, initVal);

    es.resize(n);
    for(auto&& i: id) {
        x[i] -= mi;
        // cout << x[i] << endl;
        auto par = st.query(x[i], x[i]+1);
        if(par != initVal) es[par].pb(i);
        st.update(x[i], x[i]+d[i], i);
    }
    used.resize(n);

    mint ans = 1;
    for(auto&& i : id) {
        if(!used[i]) ans *= dfs(i);
    }
    cout << ans << endl;
    return 0;
}

Measured memory_bytes: 594048