#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 998244353;
ll modpow(ll a, ll b) {
  if (b == 0) return 1;
  return modpow(a * a % mod, b / 2) * (b % 2 ? a : 1) % mod;
}
struct SegTree {
  int n;
  vector<ll> node, lazy;
  SegTree(int sz) {
    n = 1;
    while (n < sz) n *= 2;
    node.resize(2 * n - 1);
    lazy.resize(2 * n - 1);
  }
  void eval(int k, int l, int r) {
    if (lazy[k] != 0) {
      (node[k] += lazy[k]) %= mod;
      if (r - l > 1) {
        (lazy[2 * k + 1] += lazy[k] * modpow(2, mod - 2) % mod) %= mod;
        (lazy[2 * k + 2] += lazy[k] * modpow(2, mod - 2) % mod) %= mod;
      }
      lazy[k] = 0;
    }
  }
  void add(int a, int b, ll x, int k = 0, int l = 0, int r = -1) {
    if (r < 0) r = n;
    eval(k, l, r);
    if (b <= l or r <= a) return;
    if (a <= l and r <= b) {
      (lazy[k] += (r - l) * x % mod) %= mod;
      eval(k, l, r);
    } else {
      add(a, b, x, 2 * k + 1, l, (l + r) / 2);
      add(a, b, x, 2 * k + 2, (l + r) / 2, r);
      node[k] = (node[2 * k + 1] + node[2 * k + 2]) % mod;
    }
  }
  ll get(int a, int b, int k = 0, int l = 0, int r = -1) {
    if (r < 0) r = n;
    if (b <= l or r <= a) return 0;
    eval(k, l, r);
    if (a <= l and r <= b) return node[k];
    ll vl = get(a, b, 2 * k + 1, l, (l + r) / 2);
    ll vr = get(a, b, 2 * k + 2, (l + r) / 2, r);
    return (vl + vr) % mod;
  }
};
int main() {
  int n, k;
  cin >> n >> k;
  vector<int> l(n), r(n);
  for (int i = (0); i < (k); i++) cin >> l[i] >> r[i];
  SegTree st(n);
  st.add(0, 1, 1);
  for (int i = (0); i < (n); i++) {
    for (int j = (0); j < (k); j++) {
      st.add(i + l[j], min(n, i + r[j] + 1), st.get(i, i + 1));
    }
  }
  cout << st.get(n - 1, n) << endl;
  return 0;
}
