#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
const long long INF = 1e18;
int md = 998244353;
int dfs(int index, set<int> &s, int n, vector<int> &dp) {
  if (index == n) return 1;
  if (dp[index] != -1) return dp[index];
  long long ans = 0LL;
  for (auto i : s) {
    if (i + index <= n) {
      ans = (ans % md + dfs(i + index, s, n, dp) % md) % md;
    }
  }
  return dp[index] = ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, k;
  cin >> n >> k;
  vector<int> pre(n + 2);
  for (int i = 0; i < k; i++) {
    int l, r;
    cin >> l >> r;
    pre[l]++;
    pre[r + 1]--;
  }
  for (int i = 1; i <= n; i++) {
    pre[i] += pre[i - 1];
  }
  set<int> s;
  for (int i = 1; i <= n; i++) {
    if (pre[i] >= 1) s.insert(i);
  }
  vector<int> dp(n + 1, -1);
  int ans = dfs(1, s, n, dp);
  cout << ans;
  return 0;
}
