#include <bits/stdc++.h>
using namespace std;
const int mod = 998244353;
struct mint {
  long long x;
  mint(long long 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(long long 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 n, k;
int l[11], r[11];
mint dp[200005];
mint sum[200005];
int main() {
  cin >> n >> k;
  for (int i = 0; i < (k); i++) {
    cin >> l[i] >> r[i];
  }
  dp[1] = 1;
  sum[1] = 1;
  for (int i = 2; i <= n; i++) {
    mint cnt = 0;
    for (int j = 0; j < (k); j++) {
      if (i - r[j] - 1 > 0) {
        cnt += sum[i - l[j]] - sum[i - r[j] - 1];
      } else {
        cnt += sum[i - l[j]];
      }
    }
    dp[i] = cnt;
    sum[i] = sum[i - 1] + cnt;
  }
  cout << dp[n] << endl;
  return 0;
}
