#pragma GCC target("avx2")
#pragma GCC optimize("03")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std; using ld = long double; using ll = long long;
using ull = unsigned long long;
#define endl "\n"
#define FOR(i,a,b) for(int i=(a);i<=(b);i++)
#define rep(i,n) for(int i=0;i<(n);i++)
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define ALL(x) (x).begin(), (x).end()
int dx[] = {1, 0, -1, 0}; int dy[] = {0, 1, 0, -1};
constexpr int INF=1<<30;
constexpr ll LINF=1LL<<60; 
constexpr ll mod=998244353;
void flush() {cout<<flush;}
template<class T>vector<T> vec(int len, T elem) { return vector<T>(len, elem); } // auto dp = vec(52, vec(103, vec(103, INF)));
template<class T>inline bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
template<class T>inline int popcount(T a) {return __builtin_popcountll(a);}
template<class T>inline T emod(T a, T p) { return (a%p + p) % p;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec) { for (auto &v : vec) is >> v; return is; }
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {os << '\n'; for (auto v : vec) os << v << ' '; os << '\n'; return os;}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa) { os << '(' << pa.first << ',' << pa.second << ')'; return os; }
template <typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
struct MyIO {
    MyIO(){
        cin.tie(0); 
        ios::sync_with_stdio(false); 
        cout << fixed << setprecision(15);
    }
} IO_OI;
#ifdef LOCAL
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << H;
    debug_out(T...);
}
#define debug(...) \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
//-------------------
struct mint {
	ll x;
	mint(ll x=0):x(x%mod){}

	bool operator==(const mint a)const{return x==a.x;}
	bool operator!=(const mint a)const{return x!=a.x;}
	bool operator>=(const mint a){return (x >= a.x)? 1: 0;}
	bool operator<(const mint a){return !(*this>=a);}
	bool operator>(const mint a){return (x > a.x)? 1:0;}
	bool operator<=(const mint a){return !(*this>a);}
	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) {
		return (*this) *= a.inv();
	}
	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 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;  //2 square
		if (t&1) a *= *this; 
		return a;
	}
	// for prime mod
	mint inv() const {
		return pow(mod-2);
	}
    friend ostream& operator<<(ostream& os, const mint& m){
        os << m.x;
        return os;
    }
};
template <class T, class E>
struct SegmentTree {
    using F = function<T(T, T)>;
    using G = function<T(T, E)>;
    using H = function<E(E, E)>;
    using P = function<E(E, int)>;
    int n;
    F f; // minなら[](ll a, ll b) { return min(a,b);}
    G g; // pで変換したものをdataに移す時
    H h; // lazyを遷移させる時
    P p; // lazyを必要な形に変換(sumならmultipler, minなら初期のまま)
    T d1; // datの初期値かつ単位元
    E d0; // lazyの初期値
    vector<T> dat;
    vector<E> laz;
    SegmentTree(
        int n_, F f, G g, H h, T d1, E d0, vector<T> v = vector<T>(),
        P p = [](E a, int b) { return a; })
        : f(f), g(g), h(h), d1(d1), d0(d0), p(p) {
        init(n_);
        if (n_ == (int)v.size()) build(n_, v);
    }
    void init(int n_) {
        n = 1;
        while (n < n_) n *= 2;
        dat.clear();
        dat.resize(2 * n - 1, d1);
        laz.clear();
        laz.resize(2 * n - 1, d0);
    }
    void build(int n_, vector<T> v) {
        for (int i = 0; i < n_; i++) dat[i + n - 1] = v[i];
        for (int i = n - 2; i >= 0; i--)
            dat[i] = f(dat[i * 2 + 1], dat[i * 2 + 2]);
    }
    inline void eval(int len, int k) {
        if (laz[k] == d0) return;
        if (k * 2 + 1 < n * 2 - 1) {
            laz[k * 2 + 1] = h(laz[k * 2 + 1], laz[k]);
            laz[k * 2 + 2] = h(laz[k * 2 + 2], laz[k]);
        }
        dat[k] = g(dat[k], p(laz[k], len));
        laz[k] = d0;
    }
    T update(int a, int b, E x, int k, int l, int r) {
        eval(r - l, k);
        if (r <= a || b <= l) return dat[k];
        if (a <= l && r <= b) {
            laz[k] = h(laz[k], x);
            return g(dat[k], p(laz[k], r - l));
        }
        return dat[k] = f(update(a, b, x, k * 2 + 1, l, (l + r) / 2),
                          update(a, b, x, k * 2 + 2, (l + r) / 2, r));
    }
    T update(int a, int b, E x) { return update(a, b, x, 0, 0, n); }
    T _query(int a, int b, int k, int l, int r) {
        eval(r - l, k);
        if (r <= a || b <= l) return d1;
        if (a <= l && r <= b) return dat[k];
        T vl = _query(a, b, k * 2 + 1, l, (l + r) / 2);
        T vr = _query(a, b, k * 2 + 2, (l + r) / 2, r);
        return f(vl, vr);
    }
    T query(int a, int b) { return _query(a, b, 0, 0, n); }
    /* debug */
    void _print(int a) { cout << " " << dat[n-1+a];}
    void print() {
        for(int i=0; i<n; i++) _print(i);
        cout << endl;
    }
};
int main() {
    int n,k;cin>>n>>k;
    auto f = [](mint a, mint b) { return a+b;};
    auto g = [](mint a, mint b) { return a*b;};
    SegmentTree<mint,mint> ch(2*n, f, f, f, 0, 0,
                             vector<mint>(2*n, 0),g);
    vector<PII> s(k);
    rep(i,k) cin >> s[i].first >> s[i].second;
    ch.update(0,1,1);
    rep(i,n) {
        rep(j,k) ch.update(s[j].first+i, s[j].second+i+1, ch.query(i, i+1));
    }

    cout << ch.query(n-1, n) << endl;
}

Measured memory_bytes: 25908