#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll = vector<long long>;
using sll = set<long long>;
const long long ll_max = 9223372036854775807;
const long long ll_min = -9223372036854775807;
const int int_max = 2147483647;
template <typename T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <typename T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <typename T>
map<T, T> getPrimeFactor(T n) {
  map<T, T> ret;
  for (T i = 2; i * i <= n; ++i) {
    while (n % i == 0) {
      ret[i]++;
      n /= i;
    }
  }
  if (n != 1) ret[n] = 1;
  return ret;
}
template <typename T>
bool IsPrimeNumber(T num) {
  if (num <= 2)
    return true;
  else if (num % 2 == 0)
    return false;
  double sqrtNum = sqrt(num);
  for (int i = 3; i <= sqrtNum; i += 2) {
    if (num % i == 0) {
      return false;
    }
  }
  return true;
}
template <typename T>
T modinv(T a, T m) {
  T b = m, u = 1, v = 0;
  while (b) {
    long long t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  u %= m;
  if (u < 0) u += m;
  return u;
}
ll pow2(ll n, ll p, ll mod) {
  if (p == 0 || n == 1) {
    return 1;
  } else {
    ll ret = pow2(n * n % mod, p / 2, mod);
    if (p % 2 == 1) {
      ret *= n;
    }
    return ret % mod;
  }
}
ll n;
vector<pair<ll, ll>> t;
const ll mod = 998244353;
map<ll, ll> dic;
ll func(ll pos) {
  auto itr = dic.find(pos);
  if (itr != dic.end()) {
    return itr->second;
  }
  ll ret = 0;
  for (auto x : t) {
    for (ll y = x.first; y <= x.second; y++) {
      if (pos + y == n) {
        ret++;
      } else if (pos + y < n) {
        ret += func(pos + y);
      }
      ret %= mod;
    }
  }
  dic[pos] = ret;
  return ret;
}
int main() {
  ll k;
  cin >> n >> k;
  t.resize(k);
  for (ll i = 0; i < k; i++) {
    cin >> t[i].first >> t[i].second;
  }
  cout << func(1) << endl;
  return 0;
}
