#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.1415926535897923846;
const long long int MOD = 1000000007;
const long long int N = 998244353;
long long int power(long long int x, long long int n) {
  long long int res = 1;
  while (n > 0) {
    if (n & 1) res = res * x % MOD;
    x = x * x % MOD;
    n >>= 1;
  }
  return res;
}
long long int modinverse(long long int a) { return power(a, MOD - 2); }
void solve() {
  long long int n, k;
  cin >> n >> k;
  vector<long long int> seg;
  for (long long int i = 0; i < k; i++) {
    long long int l, r;
    cin >> l >> r;
    for (long long int ii = l; ii <= r; ii++) seg.push_back(ii);
  }
  sort(seg.begin(), seg.end());
  vector<long long int> dp(n + 1, 0);
  dp[1] = 1;
  for (long long int i = 2; i <= n; i++) {
    for (long long int j = 0; j < (long long int)seg.size(); j++) {
      if (seg[j] >= i) break;
      dp[i] += dp[i - seg[j]];
      dp[i] %= N;
    }
  }
  cout << dp[n] << endl;
  return;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int test = 1;
  while (test--) {
    solve();
  }
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
}
