#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int mod = 998244353;
struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + 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 += mod - a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t) 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 { return mint(*this) /= a; }
};
istream& operator>>(istream& is, mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> L(k);
  vector<int> R(k);
  for (int i = 0; i < (k); ++i) {
    cin >> L[i] >> R[i];
  }
  vector<mint> dp(n, 0);
  vector<mint> dpsum(n, 0);
  dpsum[0] = 1;
  dp[0] = 1;
  for (int i = 1; i < n; i++) {
    for (int j = 0; j < (k); ++j) {
      if (i - L[j] < 0) {
        continue;
      } else if (i - R[i - 1] < 0) {
        dp[i] += dpsum[i - L[j]];
      } else {
        dp[i] += dpsum[i - L[j]] - dpsum[i - R[j] - 1];
      }
    }
    dpsum[i] = dpsum[i - 1] + dp[i];
  }
  cout << dp[n - 1] << endl;
}
