#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-7;
const string alpha = "abcdefghijklmnopqrstuvwxyz";
int d8x[8] = {+1, +1, +1, 0, 0, -1, -1, -1};
int d8y[8] = {+1, 0, -1, +1, -1, +1, 0, -1};
int d4x[4] = {1, 0, 0, -1};
int d4y[4] = {0, -1, 1, 0};
long long power(long long x, long long y) {
  long long fk = 1;
  x = x;
  while (y > 0) {
    if (y & 1) fk = (fk * x);
    y = y >> 1;
    x = (x * x);
  }
  return fk;
}
long long sqr(long long x) { return x * x; }
template <typename T>
T gcd(T a, T b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
template <class T>
inline void chmax(T &x, T y) {
  x = max((x), (y));
}
template <class T>
inline void chmin(T &x, T y) {
  x = min((x), (y));
}
template <class T>
T abs(T x) {
  return x > 0 ? x : -x;
}
template <typename T>
T powm(T a, T b, long long m) {
  T cnt = 1;
  while (b > 0) {
    if (b % 2 == 1) cnt = (cnt * a) % m;
    b /= 2;
    a = (a * a) % m;
  }
  return cnt % m;
}
long long ncr(long long n, long long r) {
  long long fk = 1;
  if (r > n) return 0;
  if (r > n - r) r = n - r;
  for (long long i = 0; i < r; i++) {
    fk *= (n - i);
    fk /= (i + 1);
  }
  return fk;
}
const int MOD = 998244353;
const int N = 4000000;
long long n, k, dp[N], pre[N];
void solve() {
  cin >> n >> k;
  pair<long long, long long> a[k + 5];
  for (int i = 1; i <= k; ++i) {
    cin >> a[i].first >> a[i].second;
  }
  sort(a + 1, a + k + 1);
  dp[1] = 1;
  pre[1] = 1;
  for (long long i = 2; i <= n; ++i) {
    for (long long j = 1; j <= k; ++j) {
      int li = i - a[j].second;
      int ri = i - a[j].first;
      if (ri < 0) continue;
      li = max(li, 1);
      dp[i] += pre[ri] - pre[li - 1];
    }
    pre[i] = pre[i - 1] % MOD + dp[i] % MOD + MOD;
    pre[i] %= MOD;
  }
  cout << dp[n];
}
int32_t main() {
  cin.sync_with_stdio(0);
  cin.tie(0);
  cin.exceptions(cin.failbit);
  int tc = 1;
  for (int i = 1; i <= tc; ++i) {
    solve();
  }
  return 0;
}
