#include <bits/stdc++.h>
using namespace std;
const int inf = 1000000007;
const long long INF = 1e18;
int mod = 998244353;
const double eps = 1e-8;
template <typename T1, typename T2>
inline bool chmin(T1& a, T2 b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2>
inline bool chmax(T1& a, T2 b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
template <typename T, typename U>
T pow_(T a, U b) {
  return b ? pow_(a * a, b / 2) * (b % 2 ? a : 1) : 1;
}
long long modpow(long long a, long long b, long long _mod) {
  return b ? modpow(a * a % _mod, b / 2, _mod) * (b % 2 ? a : 1) % _mod : 1;
}
template <class T, class U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
  os << p.first << " " << p.second;
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& vec) {
  for (int i = 0; i < ((int)vec.size()); ++i) {
    if (i) os << " ";
    os << vec[i];
  }
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& s) {
  for (auto si : s) os << si << " ";
  return os;
}
template <typename T>
inline istream& operator>>(istream& is, vector<T>& v) {
  for (int j = 0; j < ((int)v.size()); ++j) is >> v[j];
  return is;
}
template <class T, class T2>
inline void add(T& a, T2 b) {
  (a += (b % mod + mod)) %= mod;
}
template <class T>
void operator+=(vector<T>& v, vector<T> v2) {
  for (int i = 0; i < ((int)v2.size()); ++i) v.emplace_back(v2[i]);
}
void solve();
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(12);
  int T;
  T = 1;
  while (T--) solve();
}
struct mint {
  long long x;
  mint(long long x = 0) : x((mod + x % mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += -a.x + mod) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(long long t) const {
    if (t == 0) return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) a *= *this;
    return a;
  }
  mint inv() const { return pow(mod - 2); }
  mint& operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
  friend ostream& operator<<(ostream& s, mint a) { return s << a.x; }
};
void solve() {
  int n, k;
  cin >> n >> k;
  vector<pair<int, int> > v(k);
  for (int i = 0; i < (k); ++i) cin >> v[i].first >> v[i].second;
  vector<mint> acc(n), dp(n);
  dp[0] = 1;
  for (int i = 0; i < (n); ++i) {
    if (i) {
      acc[i] += acc[i - 1];
      dp[i] = acc[i];
    }
    for (int j = 0; j < (k); ++j) {
      if (i + v[j].first >= n) continue;
      acc[i + v[j].first] += dp[i];
      acc[min(n - 1, i + v[j].second) + 1] -= dp[i];
    }
  }
  cout << dp[n - 1] << '\n';
}
