#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cout << x; }
void __print(long x) { cout << x; }
void __print(long long x) { cout << x; }
void __print(unsigned x) { cout << x; }
void __print(unsigned long x) { cout << x; }
void __print(unsigned long long x) { cout << x; }
void __print(float x) { cout << x; }
void __print(double x) { cout << x; }
void __print(long double x) { cout << x; }
void __print(char x) { cout << '\'' << x << '\''; }
void __print(const char *x) { cout << '\"' << x << '\"'; }
void __print(const string &x) { cout << '\"' << x << '\"'; }
void __print(bool x) { cout << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cout << '{';
  __print(x.first);
  cout << ',';
  __print(x.second);
  cout << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cout << '{';
  for (auto &i : x) cout << (f++ ? "," : ""), __print(i);
  cout << "}";
}
void _print() { cout << "\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cout << ", ";
  _print(v...);
}
const int mod = 998244353, mxn = 1e5 + 1;
int solve() {
  int n, k;
  cin >> n >> k;
  vector<int> gg;
  for (long long i = (0); i < (k); ++i) {
    int l, r;
    cin >> l >> r;
    for (long long j = (l); j < (r + 1); ++j) gg.push_back(j);
  }
  vector<int> dp(n + 1, 0);
  dp[1] = 1;
  for (long long i = (2); i < (n + 1); ++i) {
    for (long long j = (0); j < (gg.size()); ++j) {
      if ((i - gg[j]) <= 0) continue;
      dp[i] += dp[i - gg[j]];
      dp[i] %= mod;
    }
  }
  cout << dp[n] << "\n";
  return 0;
}
int main() {
  ios_base::sync_with_stdio(NULL);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
