#include <bits/stdc++.h>
using namespace std;
long long GCD(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return GCD(b, a % b);
}
long long lcm(long long x, long long y) { return x / GCD(x, y) * y; }
const int MAX = 510000;
const int MOD = 1000000007;
long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}
long long COM(int n, int k) {
  if (n < k) return 0;
  if (n < 0 || k < 0) return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main() {
  int N, K;
  cin >> N >> K;
  vector<int> L(K), R(K), dp(N + 100);
  set<int> s;
  for (int i = 0; i < K; i++) {
    cin >> L[i] >> R[i];
  }
  for (int i = 0; i < K; i++) {
    for (int j = L[i]; j <= R[i]; j++) {
      s.insert(j);
    }
  }
  dp[1] = 1;
  for (int i = 1; i <= N; i++) {
    for (auto d : s) {
      if (i + d <= N) {
        dp[i + d] += dp[i];
        dp[i + d] %= 998244353;
      }
    }
  }
  cout << dp[N] << endl;
  return 0;
}
