#include <bits/stdc++.h>
using namespace std;
int dy4[4] = {-1, 0, +1, 0};
int dx4[4] = {0, +1, 0, -1};
int dy8[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dx8[8] = {0, 1, 1, 1, 0, -1, -1, -1};
const long long INF = 1LL << 60;
const long long MOD = 1e9 + 7;
bool greaterSecond(const pair<int, int>& f, const pair<int, int>& s) {
  return f.second > s.second;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long conbinationMemo[100][100];
void cmemoInit() {
  for (int i = 0; i < (int)(100); i++) {
    for (int j = 0; j < (int)(100); j++) {
      conbinationMemo[i][j] = -1;
    }
  }
}
long long nCr(long long n, long long r) {
  if (conbinationMemo[n][r] != -1) return conbinationMemo[n][r];
  if (r == 0 || r == n) {
    return 1;
  } else if (r == 1) {
    return n;
  }
  return conbinationMemo[n][r] = (nCr(n - 1, r) + nCr(n - 1, r - 1));
}
long long nPr(long long n, long long r) {
  r = n - r;
  long long ret = 1;
  for (long long i = n; i >= r + 1; i--) ret *= i;
  return ret;
}
long long mod = 998244353;
int main(void) {
  long long n, k;
  cin >> n >> k;
  vector<pair<long long, long long>> vec;
  for (int i = 0; i < (int)(k); i++) {
    long long l, r;
    cin >> l >> r;
    vec.push_back({l, r});
  }
  sort((vec).begin(), (vec).end());
  long long dp[200100];
  dp[0] = 1;
  dp[1] = -1;
  long long now = 0;
  for (int i = 0; i < (int)(n); i++) {
    now += dp[i];
    now %= mod;
    for (int j = 0; j < (int)(vec.size()); j++) {
      if (i + vec[j].first >= n) break;
      dp[i + vec[j].first] += now;
      dp[i + vec[j].first] %= mod;
      if (i + vec[j].second + 1 < n) {
        dp[i + vec[j].second + 1] -= now;
        dp[i + vec[j].second + 1] %= mod;
      }
    }
  }
  while (now < 0) now += mod;
  cout << now % mod << endl;
}
