#include "bits/stdc++.h"
using namespace std;
using     ll=long long;
using    vll=vector<   ll>;
using   vvll=vector<  vll>;
using  vvvll=vector< vvll>;
using vvvvll=vector<vvvll>;
constexpr ll INF = 1LL << 60;
struct Fast{ Fast(){ cin.tie(0); ios::sync_with_stdio(false); cout<<fixed<<setprecision(numeric_limits<double>::max_digits10); } } fast;
#define REPS(i, S, E) for (ll i = (S); i <= (E); i++)
#define REP(i, N) REPS(i, 0, (N)-1)
#define DEPS(i, S, E) for (ll i = (E); i >= (S); i--)
#define DEP(i, N) DEPS(i, 0, (N)-1)
#define rep(i, S, E)  for (ll i = (S); i <= (E); i++)
#define dep(i, E, S)  for (ll i = (E); i >= (S); i--)
#define each(e, v) for (auto&& e : v)
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
template<class T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; }return false; }
template<class T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; }return false; }
template<class T> inline T MaxE(vector<T>&v,ll S,ll E){ T m=v[S]; rep(i,S,E)chmax(m,v[i]); return m; }
template<class T> inline T MinE(vector<T>&v,ll S,ll E){ T m=v[S]; rep(i,S,E)chmin(m,v[i]); return m; }
template<class T> inline T MaxE(vector<T> &v) { return MaxE(v,0,(ll)v.size()-1); }
template<class T> inline T MinE(vector<T> &v) { return MinE(v,0,(ll)v.size()-1); }
template<class T> inline T Sum(vector<T> &v,ll S,ll E){ T s=T(); rep(i,S,E)s+=v[i]; return s; }
template<class T> inline T Sum(vector<T> &v) { return Sum(v,0,v.size()-1); }
template<class T> inline ll sz(T &v){ return (ll)v.size(); }
inline ll CEIL(ll a,ll b){ return (a<0) ? -(-a/b) : (a+b-1)/b; }
inline ll FLOOR(ll a,ll b){ return -CEIL(-a,b); }

template<ll MOD> struct mll_{
	ll val;
	mll_(ll v = 0): val(v % MOD){ if (val < 0) val += MOD; }
	mll_ operator - () const { return -val; }
	mll_ operator + (const mll_ &b) const { return val + b.val; }
	mll_ operator - (const mll_ &b) const { return val - b.val; }
	mll_ operator * (const mll_ &b) const { return val * b.val; }
	mll_ operator / (const mll_ &b) const { return mll_(*this) /= b; }
	mll_ operator + (ll b) const { return *this + mll_(b); }
	mll_ operator - (ll b) const { return *this - mll_(b); }
	mll_ operator * (ll b) const { return *this * mll_(b); }
	friend mll_ operator + (ll a,const mll_ &b) { return b + a; }
	friend mll_ operator - (ll a,const mll_ &b) { return -b + a; }
	friend mll_ operator * (ll a,const mll_ &b) { return b * a; }
	friend mll_ operator / (ll a,const mll_ &b) { return mll_(a)/b; }
	mll_ &operator += (const mll_ &b) { val=(val+b.val)%MOD; return *this; }
	mll_ &operator -= (const mll_ &b) { val=(val+MOD-b.val)%MOD; return *this; }
	mll_ &operator *= (const mll_ &b) { val=(val*b.val)%MOD; return *this; }
	mll_ &operator /= (const mll_ &b) {
		ll c=b.val,d=MOD,u=1,v=0;
		while (d){
			ll t = c / d;
			c -= t * d; swap(c,d);
			u -= t * v; swap(u,v);
		}
		val = val * u % MOD;
		if (val < 0) val += MOD;
		return *this;
	}
	mll_ &operator += (ll b) { return *this += mll_(b); }
	mll_ &operator -= (ll b) { return *this -= mll_(b); }
	mll_ &operator *= (ll b) { return *this *= mll_(b); }
	mll_ &operator /= (ll b) { return *this /= mll_(b); }
	bool operator == (const mll_ &b) { return val == b.val; }
	bool operator != (const mll_ &b) { return val != b.val; }
	bool operator == (ll b) { return *this == mll_(b); }
	bool operator != (ll b) { return *this != mll_(b); }
	friend bool operator == (ll a,const mll_ &b) { return mll_(a) == b.val; }
	friend bool operator != (ll a,const mll_ &b) { return mll_(a) != b.val; }
	friend ostream &operator << (ostream &os,const mll_ &a) { return os << a.val; }
	friend istream &operator >> (istream &is,mll_ &a) { return is >> a.val; }
	static mll_ Combination(ll a,ll b){
		chmin(b,a-b);
		if (b<0) return mll_(0);
		mll_ c = 1;
		rep(i,0,b-1) c *= a-i;
		rep(i,0,b-1) c /= i+1;
		return c;
	}
};
using mll = mll_<998244353LL>;
using vmll    = std::vector<mll>;
using vvmll   = std::vector<vmll>;
using vvvmll  = std::vector<vvmll>;
using vvvvmll = std::vector<vvvmll>;

//vector用テンプレート
template<class T> inline vector<T>& operator+=(vector<T> &a,const vector<T> &b){ for (ll i=0; i<(ll)a.size(); i++) a[i]+=b[i];  return a; }
template<class T> inline vector<T>& operator-=(vector<T> &a,const vector<T> &b){ for (ll i=0; i<(ll)a.size(); i++) a[i]-=b[i];  return a; }
template<class T> inline vector<T>& operator*=(vector<T> &a,const vector<T> &b){ for (ll i=0; i<(ll)a.size(); i++) a[i]*=b[i];  return a; }
template<class T> inline vector<T>& operator/=(vector<T> &a,const vector<T> &b){ for (ll i=0; i<(ll)a.size(); i++) a[i]/=b[i];  return a; }
template<class T> inline vector<T>& operator%=(vector<T> &a,const vector<T> &b){ for (ll i=0; i<(ll)a.size(); i++) a[i]%=b[i];  return a; }
template<class T,class S> inline vector<T>& operator+=(vector<T> &a,S b){ for (T &e: a) e+=b;  return a; }
template<class T,class S> inline vector<T>& operator-=(vector<T> &a,S b){ for (T &e: a) e-=b;  return a; }
template<class T,class S> inline vector<T>& operator*=(vector<T> &a,S b){ for (T &e: a) e*=b;  return a; }
template<class T,class S> inline vector<T>& operator/=(vector<T> &a,S b){ for (T &e: a) e/=b;  return a; }
template<class T,class S> inline vector<T>& operator%=(vector<T> &a,S b){ for (T &e: a) e%=b;  return a; }
template<class T,class S> inline vector<T> operator+(const vector<T> &a,S b){ vector<T> c=a; return c+=b; }
template<class T,class S> inline vector<T> operator-(const vector<T> &a,S b){ vector<T> c=a; return c-=b; }
template<class T,class S> inline vector<T> operator*(const vector<T> &a,S b){ vector<T> c=a; return c*=b; }
template<class T,class S> inline vector<T> operator/(const vector<T> &a,S b){ vector<T> c=a; return c/=b; }
template<class T,class S> inline vector<T> operator%(const vector<T> &a,S b){ vector<T> c=a; return c%=b; }
template<class T,class S> inline vector<T> operator-(S b,const vector<T> &a){ vector<T> c=-a; return c+=b; }
template<class T> inline vector<T> operator-(const vector<T> &a){ vector<T> c=a; return c*=(-1); }
template<class T> inline ostream &operator<<(ostream &os,const vector<T> &a){ for (ll i=0; i<(ll)a.size(); i++) os<<(i>0?" ":"")<<a[i];  return os; }

#if 0
#include <atcoder/all>
using namespace atcoder;
#endif


template <class T> struct CumulativeSumG{
	ll s=0,e=-1;  vector<T> cum;
	CumulativeSumG(){};
	CumulativeSumG(vector<T> &v): e(v.size()-1),cum(e+2) { Ini(v); }
	CumulativeSumG(vector<T> &v,ll S,ll E): s(S),e(E),cum(e-s+2){ Ini(v); }
	void init(vector<T> &v){ e=v.size()-1; cum.resize(e+2); Ini(v); }
	void init(vector<T> &v,ll S,ll E){ s=S; e=E; cum.resize(e-s+2); Ini(v); }
	void add(T x) { e++; cum.push_back(cum.back() + x); }
	T operator () (ll begin,ll end){ return cum[end+1-s] - cum[begin-s]; }
	void Ini(vector<T> &v) { rep(i,s,e) cum[i+1-s] = cum[i-s] + v[i]; }
};
using CumulativeSum = CumulativeSumG<mll>;




void solve()
{
	ll n,K;  cin >> n >> K;
	vector<pair<ll,ll>> lr(K);
	rep(i,0,K-1){ ll l; ll r; cin>>l>>r; lr[i]={l,r}; }

	vmll dp_(n);
	auto dp = [&](ll i)->mll&{
		//static mll dmy=0;
		return dp_[i];
	};
	dp(0)=1;

	CumulativeSum cm_(dp_,0,0);
	auto cm=[&](ll l,ll r){
		if (r<0)return mll(0);
		if (l<0) l=0;
		return cm_(l,r);
	};

	rep(i,1,n-1){
		rep(k,0,K-1){
			ll l,r;  tie(l,r) = lr[k];
			dp(i)+=cm(i-r,i-l);
		}
		cm_.add(dp(i));
	}
	cout << dp(n-1) << '\n';
}


int main(){
#if 1
	solve();
#else
	ll t;  cin >> t;
	rep(i, 0, t-1){
		solve();
	}
#endif
	return 0;
}


Measured memory_bytes: 6856