#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define limit(x,l,r) max(l,min(x,r))
#define lims(x,l,r) (x = max(l,min(x,r)))
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define show(x) cout<<#x<<" = "<<x<<endl;
#define print(x)cout<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef tuple<int,int,int> T;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
typedef vector<T> vt;
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 {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= 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 {
    mint res(*this);
    return res /= a;
  }
};

template <typename T>
struct BIT {
    int n;             // 要素数
    vector<T> bit[2];  // データの格納先
    BIT(int n_) { init(n_); }
    void init(int n_) {
        n = n_ + 1;
        for (int p = 0; p < 2; p++) bit[p].assign(n, 0);
    }
    void add_sub(int p, int i, T x) {
        for (int idx = i; idx < n; idx += (idx & -idx)) {
            bit[p][idx] += x;
        }
    }
    void add(int l, int r, T x) {  // [l,r) に加算
        add_sub(0, l, -x * (l - 1));
        add_sub(0, r, x * (r - 1));
        add_sub(1, l, x);
        add_sub(1, r, -x);
    }
    T sum_sub(int p, int i) {
        T s(0);
        for (int idx = i; idx > 0; idx -= (idx & -idx)) {
            s += bit[p][idx];
        }
        return s;
    }
    T sum(int i) { return sum_sub(0, i) + sum_sub(1, i) * i; }

    T query(int l, int r) { return sum(r - 1) - sum(l - 1); }
};
   
int range[202020];
int main() {
  int n,k;
  cin >>n >>k;
  vi r(n),l(n);
  BIT<mint> dp(n*2);
  dp.add(1,2,1);
  rep(i,k){
    cin >> l[i] >>r[i];
  }
  srep(i,1,n+2){
    rep(j,k){
      int ll = i+l[j];
      int rr = i+r[j]+1;
      //cout<<ll<<"-"<<rr<<endl;
      auto now = dp.query(i,i+1);
      dp.add(ll,rr,now);
    }
  }
  // rep(i,n+1){
  //   cout<<dp[i].x<<" ";
  // }
  // cout<<endl;

  cout<<dp.query(n,n+1).x<<endl;
  
  return 0;
}

Measured memory_bytes: 11176