#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
#include <numeric>
#include <tuple>
#include <limits>

template <class T, class U>
inline bool chmin(T& lhs, const U& rhs) {
  if (lhs > rhs) {
    lhs = rhs;
    return true;
  }
  return false;
}

template <class T, class U>
inline bool chmax(T& lhs, const U& rhs) {
  if (lhs < rhs) {
    lhs = rhs;
    return true;
  }
  return false;
}

// [l, r) from l to r
struct range {
  struct itr {
    int i;
    constexpr itr(int i_): i(i_) { }
    constexpr void operator ++ () { ++i; }
    constexpr int operator * () const { return i; }
    constexpr bool operator != (itr x) const { return i != x.i; }
  };
  const itr l, r;
  constexpr range(int l_, int r_): l(l_), r(std::max(l_, r_)) { }
  constexpr itr begin() const { return l; }
  constexpr itr end() const { return r; }
};

// [l, r) from r to l
struct revrange {
  struct itr {
    int i;
    constexpr itr(int i_): i(i_) { }
    constexpr void operator ++ () { --i; }
    constexpr int operator * () const { return i; }
    constexpr bool operator != (itr x) const { return i != x.i; }
  };
  const itr r, l;
  constexpr revrange(int l_, int r_): l(l_ - 1), r(std::max(l_, r_) - 1) { }
  constexpr itr begin() const { return r; }
  constexpr itr end() const { return l; }
};

template <class T>
class segment_tree {
public:
  using value_type = typename T::value_type;
  using effector_type = typename T::effector_type;
  using value_operation = typename T::value_operation;
  using merge_operation = typename T::merge_operation;

private:
  int size;
  const value_operation op1;
  const merge_operation op2;
  std::vector<value_type> node;

  void update() {
    for (int k = size - 1; k > 0; --k) {
      node[k] = op1(node[k << 1 | 0], node[k << 1 | 1]);
    }
  }

public:
  segment_tree(): op1(value_operation()), op2(merge_operation()) { }
  segment_tree(int size_, const value_type &initial_ = value_operation().identity):
    op1(value_operation()), op2(merge_operation())
  { init(size_, initial_); }
  segment_tree(const std::vector<value_type> &node_):
    op1(value_operation()), op2(merge_operation())
  { build(node_); }

  void init(int size_, const value_type &initial_ = value_operation().identity) {
    size = 1;
    while (size < size_) {
      size <<= 1;
    }
    node.assign(size << 1, initial_);
    update();
  }
  void build(const std::vector<value_type> &node_) {
    init(node_.size());
    assign(node_.begin(), node_.end(), 0);
  }

  void modify(int i, const effector_type &x) {
    i += size;
    node[i] = op2(node[i], x);
    while (i > 1) {
      i >>= 1;
      node[i] = op1(node[i << 1 | 0], node[i << 1 | 1]);
    }
  }
  template <class U>
  void modify(U begin, U end, int i) {
    i += size;
    while (begin != end) {
      node[i] = op2(node[i], *begin);
      ++i;
      ++begin;
    }
    update();
  }

  void assign(int i, const value_type &x) {
    i += size;
    node[i] = x;
    while (i > 1) {
      i >>= 1;
      node[i] = op1(node[i << 1 | 0], node[i << 1 | 1]);
    } 
  }
  template <class U>
  void assign(U begin, U end, int i) {
    i += size;
    while (begin != end) {
      node[i] = *begin;
      ++i;
      ++begin;
    }
    update();
  }

  value_type operator [] (int i) const { 
    return node[i + size];
  }
  value_type fold(int l, int r) const {
    l += size;
    r += size;
    value_type resl = op1.identity;
    value_type resr = op1.identity;
    while (l < r) {
      if (l & 1) {
        resl = op1(resl, node[l++]);
      }
      if (r & 1) {
        resr = op1(node[--r], resr);
      }
      l >>= 1;
      r >>= 1;
    }
    return op1(resl, resr);
  }

};

template <class T>
struct range_max_single_assign {
  using value_type = T;
  using effector_type = T;
  struct value_operation {
    value_type identity = std::numeric_limits<T>::min();
    value_type operator () (const value_type &x, const value_type &y) const {
      return x > y ? x : y;
    }
  };
  struct merge_operation {
    value_type operator () (const value_type &x, const effector_type &y) const {
      return y;
    }
  };
};

template <class T>
class modulo_int {
public:
  static constexpr int mod = T::value;
  static_assert(mod > 0, "mod must be positive");
private:
  long long value;
  constexpr void normalize() {
    value %= mod;
    if (value < 0) value += mod;
  }
public:
  constexpr modulo_int(long long value_ = 0): value(value_) { normalize(); }
  constexpr modulo_int operator - () const { return modulo_int(mod - value); }
  constexpr modulo_int operator ~ () const { return power(mod - 2); }
  constexpr long long operator () () const { return value; }
  constexpr modulo_int operator + (const modulo_int& rhs) const { return modulo_int(*this) += rhs; }
  constexpr modulo_int& operator += (const modulo_int& rhs) {
    if ((value += rhs.value) >= mod) value -= mod;
    return (*this);
  }
  constexpr modulo_int operator - (const modulo_int& rhs) const { return modulo_int(*this) -= rhs; }
  constexpr modulo_int& operator -= (const modulo_int& rhs) {
    if ((value += mod - rhs.value) >= mod) value -= mod;
    return (*this);
  }
  constexpr modulo_int operator * (const modulo_int& rhs) const { return modulo_int(*this) *= rhs; }
  constexpr modulo_int& operator *= (const modulo_int& rhs) {
    (value *= rhs.value) %= mod;
    return (*this);
  }
  constexpr modulo_int operator / (const modulo_int& rhs) const { return modulo_int(*this) /= rhs; }
  constexpr modulo_int& operator /= (const modulo_int& rhs) {
    return (*this) *= ~rhs;
  }
  constexpr modulo_int power (unsigned long long pow) const {
    modulo_int result(1), mult(*this);
    while (pow > 0) {
      if (pow & 1) result *= mult;
      mult *= mult;
      pow >>= 1;
    }
    return result;
  }
  friend std::istream& operator >> (std::istream& stream, modulo_int& lhs) {
    stream >> lhs.value;
    lhs.normalize();
    return stream;
  }
  friend std::ostream& operator << (std::ostream& stream, const modulo_int& rhs) {
    return stream << rhs.value;
  }
};

using modint = modulo_int<std::integral_constant<int, 998244353>>;

int main() {
  int N;
  std::cin >> N;
  std::vector<std::pair<int, int>> robot(N);
  for (auto &x: robot) {
    std::cin >> x.first >> x.second;
  }
  std::sort(robot.begin(), robot.end());
  std::vector<int> X(N), D(N);
  for (int i: range(0, N)) {
    std::tie(X[i], D[i]) = robot[i];
  }
  segment_tree<range_max_single_assign<int>> seg(N);
  for (int i: revrange(0, N)) {
    int t = std::lower_bound(X.begin(), X.end(), X[i] + D[i]) - X.begin() - 1;
    if (t == i) {
      seg.assign(i, t);
    }
    else {
      seg.assign(i, seg.fold(i + 1, t + 1));
    }
  }
  std::vector<std::vector<int>> query(N);
  for (int i: range(0, N)) {
    query[seg[i]].push_back(i);
  }
  std::vector<modint> dp(N + 1);
  dp[0] = 1;
  for (int i: range(0, N)) {
    dp[i + 1] += dp[i];
    for (int t: query[i]) {
      dp[i + 1] += dp[t];
    }
  }
  std::cout << dp[N] << '\n';
  return 0;
}


Measured memory_bytes: 14976