#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using P = pair<int, int>;
using PL = pair<lint, lint>;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
#define ALL(a)  (a).begin(),(a).end()
constexpr int MOD = 998244353;
constexpr lint B1 = 1532834020;
constexpr lint M1 = 2147482409;
constexpr lint B2 = 1388622299;
constexpr lint M2 = 2147478017;
constexpr int INF = 2147483647;
void yes(bool expr) {cout << (expr ? "Yes" : "No") << "\n";}
template<class T>void chmax(T &a, const T &b) { if (a<b) a=b; }
template<class T>void chmin(T &a, const T &b) { if (b<a) a=b; }
mint op(mint a, mint b) {return a + b;}
mint e() {return (mint)0;}
int main()
{
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  lint N, K;
  cin >> N >> K;
  vector<int> L(K), R(K);
  REP(i, K) cin >> L[i] >> R[i];
  segtree<mint, op, e> seg(N);
  seg.set(0, (mint)1);
  FOR(i, 1, N) {
    mint val = 0;
    REP(j, K) val += seg.prod(max(0, i-R[j]), max(0, i-L[j]+1));
    seg.set(i, val);
  }
  cout << seg.get(N-1).val() << endl;
}