#line 1 "all_in/working/temp0.cpp"
//#define NDEBUG
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <utility>
#include <vector>

namespace n91 {

using i8 = std::int_fast8_t;
using i32 = std::int_fast32_t;
using i64 = std::int_fast64_t;
using u8 = std::uint_fast8_t;
using u32 = std::uint_fast32_t;
using u64 = std::uint_fast64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

struct rep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { ++i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr rep(const usize f, const usize l) noexcept
      : f(std::min(f, l)), l(l) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
struct revrep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { --i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr revrep(const usize f, const usize l) noexcept
      : f(l - 1), l(std::min(f, l) - 1) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
template <class T> auto md_vec(const usize n, const T &value) {
  return std::vector<T>(n, value);
}
template <class... Args> auto md_vec(const usize n, Args... args) {
  return std::vector<decltype(md_vec(args...))>(n, md_vec(args...));
}
template <class T> constexpr T difference(const T &a, const T &b) noexcept {
  return a < b ? b - a : a - b;
}
template <class T> void chmin(T &a, const T &b) noexcept {
  if (b < a)
    a = b;
}
template <class T> void chmax(T &a, const T &b) noexcept {
  if (a < b)
    a = b;
}
template <class F> class rec_lambda {
  F f;

public:
  rec_lambda(F &&f) : f(std::move(f)) {}
  template <class... Args> auto operator()(Args &&... args) const {
    return f(*this, std::forward<Args>(args)...);
  }
};
template <class F> auto make_rec(F &&f) { return rec_lambda<F>(std::move(f)); }
template <class T> T scan() {
  T ret;
  std::cin >> ret;
  return ret;
}

} // namespace n91

#line 1 "Library/data_structure/segment_tree.cpp"
#include <cassert>
#include <cstddef>
#include <vector>

template <class Monoid> class segment_tree {
public:
  using T = typename Monoid::value_type;
  using size_t = std::size_t;

private:
  std::vector<T> tree;

  template <class F>
  size_t search_subtree(size_t index, const F f, T fold_l) const {
    while (index < size()) {
      const T temp = Monoid::operation(fold_l, tree[index * 2]);
      if (!f(temp)) {
        index = index * 2;
      } else {
        fold_l = temp;
        index = index * 2 + 1;
      }
    }
    return index - size();
  }

public:
  segment_tree() = default;
  explicit segment_tree(const size_t n) : tree(n * 2, Monoid::identity) {}

  size_t size() const noexcept { return tree.size() / 2; }

  T fold(size_t first, size_t last) const {
    assert(first <= last);
    assert(last <= size());
    first += size();
    last += size();
    T fold_l = Monoid::identity;
    T fold_r = Monoid::identity;
    while (first != last) {
      if (first % 2 != 0) {
        fold_l = Monoid::operation(fold_l, tree[first]);
        first += 1;
      }
      first /= 2;
      if (last % 2 != 0) {
        last -= 1;
        fold_r = Monoid::operation(tree[last], fold_r);
      }
      last /= 2;
    }
    return Monoid::operation(fold_l, fold_r);
  }
  template <class F> size_t search(size_t first, size_t last, const F f) const {
    assert(first <= last);
    assert(last <= size());
    first += size();
    last += size();
    const size_t last_cp = last;
    size_t shift = 0;
    T fold_l = Monoid::identity;
    while (first != last) {
      if (first % 2 != 0) {
        const T temp = Monoid::operation(fold_l, tree[first]);
        if (!f(temp))
          return search_subtree(first, f, fold_l);
        fold_l = temp;
        first += 1;
      }
      first /= 2;
      last /= 2;
      shift += 1;
    }
    while (shift != 0) {
      shift -= 1;
      last = last_cp >> shift;
      if (last % 2 != 0) {
        last -= 1;
        const T temp = Monoid::operation(fold_l, tree[last]);
        if (!f(temp))
          return search_subtree(last, f, fold_l);
        fold_l = temp;
      }
    }
    return last_cp - size();
  }

  void update(size_t index, const T x) {
    assert(index < size());
    index += size();
    tree[index] = x;
    while (index != 1) {
      index /= 2;
      tree[index] = Monoid::operation(tree[index * 2], tree[index * 2 + 1]);
    }
  }
};

/**
 * @brief Segment Tree
 * @docs docs/segment_tree.md
 * @see https://scrapbox.io/data-structures/Segment_Tree
 */
#line 1 "Library/other/modint.cpp"
#include <cstdint>

template <std::uint_fast64_t Modulus> class modint {
  using u64 = std::uint_fast64_t;

public:
  using value_type = u64;

  static constexpr u64 mod = Modulus;

private:
  static_assert(mod < static_cast<u64>(1) << 32,
                "Modulus must be less than 2**32");

  u64 v;

  constexpr modint &negate() noexcept {
    if (v != 0)
      v = mod - v;
    return *this;
  }

public:
  constexpr modint(const u64 x = 0) noexcept : v(x % mod) {}
  constexpr u64 &value() noexcept { return v; }
  constexpr const u64 &value() const noexcept { return v; }
  constexpr modint operator+() const noexcept { return modint(*this); }
  constexpr modint operator-() const noexcept { return modint(*this).negate(); }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    v += rhs.v;
    if (v >= mod)
      v -= mod;
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (v < rhs.v)
      v += mod;
    v -= rhs.v;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    v = v * rhs.v % mod;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    u64 exp = mod - 2;
    while (exp != 0) {
      if (exp % 2 != 0)
        *this *= rhs;
      rhs *= rhs;
      exp /= 2;
    }
    return *this;
  }
};
template <std::uint_fast64_t Modulus>
constexpr typename modint<Modulus>::u64 modint<Modulus>::mod;
#line 85 "all_in/working/temp0.cpp"

#include <algorithm>
#include <limits>

template <class T> class max_monoid {
public:
  using value_type = T;
  static constexpr T operation(const T &x, const T &y) noexcept {
    return std::max(x, y);
  }
  static constexpr T identity = std::numeric_limits<T>::lowest();
};
template <class T> constexpr T max_monoid<T>::identity;

namespace n91 {

void main_() {
  using mint = modint<998244353>;
  /*
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  //*/
  const usize n = scan<usize>();
  struct p_t {
    i32 x;
    i32 d;
  };
  std::vector<p_t> ps(n);
  for (auto &e : ps) {
    std::cin >> e.x >> e.d;
  }
  std::sort(ps.begin(), ps.end(), [](auto &&l, auto &&r) { return l.x < r.x; });
  segment_tree<max_monoid<usize>> seg(n);
  for (const usize i : revrep(0, n)) {
    seg.update(i, i + 1);
    const usize r = std::partition_point(
                        ps.begin(), ps.end(),
                        [&](auto &&v) { return v.x < ps[i].x + ps[i].d; }) -
                    ps.begin();
    seg.update(i, seg.fold(i, r));
  }
  const auto solve =
      make_rec([&](auto &&solve, const usize l, const usize r) -> mint {
        if (l == r)
          return 1;
        const usize t = seg.fold(l, l + 1);
        return (solve(l + 1, t) + 1) * solve(t, r);
      });
  std::cout << solve(0, n).value() << std::endl;
}

} // namespace n91

int main() {
  n91::main_();
  return 0;
}


Measured memory_bytes: 15872