#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int mod = 998244353;
int n, k, l[10], r[10], a[200001], b[200002] = {0, 1, -1};
int main() {
  cin >> n >> k;
  for (int i = 0; i < k; ++i) {
    cin >> l[i] >> r[i];
  }
  for (int i = 1; i < n; ++i) {
    a[i] = (a[i - 1] + b[i]) % mod;
    for (int j = 0; j < k; ++j) {
      int x, y;
      x = min(n + 1, i + l[j]);
      y = min(n + 1, i + r[j] + 1);
      b[x] += a[i];
      b[y] %= mod;
      b[y] -= a[i];
      b[y] %= mod;
    }
  }
  a[n] = (a[n - 1] + b[n]) % mod;
  if (a[n] < 0) a[n] += mod;
  cout << a[n] << endl;
}
