#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
long long int power(long long int x, long long int y) {
  long long int ans = 1;
  x %= 998244353;
  while (y) {
    if (y & 1) ans = (x * ans) % 998244353;
    x = (x * x) % 998244353;
    y >>= 1;
  }
  return ans;
}
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
long long int helper(vector<long long int> &dp, int si,
                     vector<long long int> &second, int &in) {
  long long int n = dp.size() - 1;
  if (si > n) return 0;
  if (dp[si] != -1) return dp[si];
  dp[si] = 0;
  for (long long int i = 0; i < in; i++) {
    (dp[si] += helper(dp, si + second[i], second, in)) %= 998244353;
  }
  return dp[si];
}
void solve() {
  int n, k;
  cin >> n >> k;
  vector<long long int> second(n);
  int in = 0;
  for (int i = 0; i < k; i++) {
    long long int x, y;
    cin >> x >> y;
    for (long long int j = x; j <= y; j++) {
      second[in++] = j;
    }
  }
  vector<long long int> dp(n + 1, -1);
  dp[n] = 1;
  cout << helper(dp, 1, second, in) << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
}
