#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const long long INF = 1LL << 60;
const ll mod = 998244353;
int main() {
  int N, K;
  cin >> N >> K;
  set<int> L, R;
  vector<int> V;
  for (int i = 0; i < K; i++) {
    int l, r;
    cin >> l >> r;
    for (int j = l; j <= r; j++) {
      V.push_back(j);
    }
  }
  vector<ll> dp(N + 1, 0);
  dp[0] = 0;
  dp[1] = 1;
  int M = V.size();
  sort(V.begin(), V.end());
  for (int i = 2; i <= N; i++) {
    for (int j = 0; j < M; j++) {
      if (i - V[j] < 1)
        break;
      else if (i - V[j] >= 1) {
        dp[i] += (dp[i - V[j]]);
        dp[i] %= mod;
      }
    }
  }
  dp[N] %= mod;
  cout << dp[N] << endl;
}
