#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
#define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define reps(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
#define rrep(i, n) for(int i=((int)(n)-1); i>=0; --i)
#define rreps(i, n) for(int i=((int)(n)); i>0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pl(s) cout << (s) << "\n";
#define pls(...) {bool space = false; for(auto i : __VA_ARGS__) (cout << (space?" ":"") << i), space = true; cout << "\n";}
#define plexit(s) {cout << (s) << "\n"; exit(0);}
#define yes(s) cout << ((s)?"Yes":"No") << "\n";
#ifdef __LOCAL
#include <dump.hpp>
#define dump(...) DUMPOUT << "  " << string(#__VA_ARGS__) << ": " << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl << "    ", dump_func(__VA_ARGS__)
#else
#define dump(...)
#endif
template<typename T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<typename T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
struct IOInit { IOInit() { cin.tie(nullptr); ios::sync_with_stdio(false); dump("READY"); /*cout << unitbuf;*/} } IO_INIT;
using ll = long long; using ull = unsigned long long; using ld = long double;
template<typename T = int> using V = vector<T>; template<typename T = int> using P = pair<T, T>;
using Vi = V<int>; using Vl = V<ll>; using Vd = V<ld>; using VVi = V<Vi>; using VVl = V<Vl>; using Pi = P<int>; using Pl = P<ll>; using Pd = P<ld>;
constexpr ll MOD = 1000000007; constexpr int INF = (1 << 30) - 1; constexpr ll INFL = 1LL << 60; constexpr ld EPS = 1e-12; constexpr ld PI = 3.141592653589793238462643383279;

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
//const int mod = 1000000007;
const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}

signed main(void) {
  int n, k; cin >> n >> k;
  V<Pi> p;
  rep(i,k) {
    int l, r; cin >> l >> r;
    ++r;
    p.emplace_back(l, r);
  }
  V<mint> dp(n);
  dp[0] = 1; dp[1] = -1;
  rep(i,n) {
    if (i > 0) dp[i] += dp[i-1];
    rep(j,k) {
      int l, r; tie(l,r) = p[j];
      if (i+l < n) dp[i+l] += dp[i];
      if (i+r < n) dp[i+r] -= dp[i];
    }
  }
  dump(dp);
  pl(dp[n-1])
  return 0;
}


Measured memory_bytes: 4776