#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<int>;
using VL = vector<ll>;
using VS = vector<string>;
template<class T> using PQ = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i,a,n) for(int i=(a);i<(n);++i)
#define eFOR(i,a,n) for(int i=(a);i<=(n);++i)
#define rFOR(i,a,n) for(int i=(n)-1;i>=(a);--i)
#define erFOR(i,a,n) for(int i=(n);i>=(a);--i)
#define each(i, a) for(auto &i : a)
#define SORT(a) sort(a.begin(),a.end())
#define rSORT(a) sort(a.rbegin(),a.rend())
#define fSORT(a,f) sort(a.begin(),a.end(),f)
#define all(a) a.begin(),a.end()
#define out(y,x) ((y)<0||h<=(y)||(x)<0||w<=(x))
#define tp(a,i) get<i>(a)
#define line cout << "-----------------------------\n" 
#define ENDL(i,n) ((i) == (n) - 1 ? "\n" : " ")
#define elif else if
#define stop system("pause")
constexpr ll INF = 1000000000;
constexpr ll LLINF = 1LL << 60;
constexpr ll mod = 1000000007;
constexpr ll MOD = 998244353;
constexpr ld eps = 1e-10;
constexpr ld pi = 3.1415926535897932;
template<class T>inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; }return false; }
template<class T>inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; }return false; }
inline void init() { cin.tie(nullptr); cout.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); }
template<class T>inline istream& operator>>(istream& is, vector<T>& v) { for (auto& a : v)is >> a; return is; }
template<class T>inline istream& operator>>(istream& is, deque<T>& v) { for (auto& a : v)is >> a; return is; }
template<class T, class U>inline istream& operator>>(istream& is, pair<T, U>& p) { is >> p.first >> p.second; return is; }
template<class T>inline vector<T> vec(size_t a) { return vector<T>(a); }
template<class T>inline vector<T> defvec(T def, size_t a) { return vector<T>(a, def); }
template<class T, class... Ts>inline auto vec(size_t a, Ts... ts) { return vector<decltype(vec<T>(ts...))>(a, vec<T>(ts...)); }
template<class T, class... Ts>inline auto defvec(T def, size_t a, Ts... ts) { return vector<decltype(defvec<T>(def, ts...))>(a, defvec<T>(def, ts...)); }
template<class T>inline void print(const T& a) { cout << a << "\n"; }
template<class T, class... Ts>inline void print(const T& a, const Ts&... ts) { cout << a << " "; print(ts...); }
template<class T>inline void print(const vector<T>& v) { for (int i = 0; i < v.size(); ++i)cout << v[i] << (i == v.size() - 1 ? "\n" : " "); }
template<class T>inline void print(const vector<vector<T>>& v) { for (auto& a : v)print(a); }
inline string reversed(const string& s) { string t = s; reverse(all(t)); return t; }

template<class Op> class LazySegmentTree {
	using T = typename Op::T;
	using LT = typename Op::LT;
	int n, len, hei;
	vector<T> dat, lazy;
	vector<pair<int, int>> range;

	void evaluate(int k) {
		if (lazy[k] == Op::lazy_unit)return;
		dat[k] = Op::propagate(dat[k], lazy[k],
			range[k].second - range[k].first);
		if (k < len) {
			lazy[k << 1] = Op::lazy_merge(lazy[k << 1], lazy[k]);
			lazy[k << 1 | 1] = Op::lazy_merge(lazy[k << 1 | 1], lazy[k]);
		}
		lazy[k] = Op::lazy_unit;
	}
public:
	LazySegmentTree(const int _n) : n(_n) {
		for (len = 1, hei = 0; len < n; len <<= 1, ++hei);
		dat.resize(len << 1, Op::unit);
		lazy.resize(len << 1);
		range.resize(len << 1);
		for (int i = 0; i < len; ++i)
			range[i + len] = make_pair(i, i + 1);
		for (int i = len - 1; 0 < i; --i)
			range[i] = make_pair(range[i << 1].first, range[i << 1 | 1].second);
	}
	LazySegmentTree(const vector<T>& v) : n(v.size()) {
		for (len = 1, hei = 0; len < n; len <<= 1, ++hei);
		dat.resize(len << 1, Op::unit);
		lazy.resize(len << 1);
		range.resize(len << 1);
		for (int i = 0; i < n; ++i)dat[i + len] = v[i];
		for (int i = 0; i < len; ++i)
			range[i + len] = make_pair(i, i + 1);
		for (int i = len - 1; 0 < i; --i) {
			dat[i] = Op::merge(dat[i << 1], dat[i << 1 | 1]);
			range[i] = make_pair(range[i << 1].first, range[i << 1 | 1].second);
		}
	}
	inline void update(int x, int y, const LT a) {
		int l = x + len, r = y + len - 1;
		for (int i = hei; 0 < i; --i) {
			evaluate(l >> i);
			evaluate(r >> i);
		}

		for (++r; l < r; l >>= 1, r >>= 1) {
			if (l & 1) {
				lazy[l] = Op::lazy_merge(lazy[l], a);
				evaluate(l);
				++l;
			}
			if (r & 1) {
				--r;
				lazy[r] = Op::lazy_merge(lazy[r], a);
				evaluate(r);
			}
		}
		l = x + len >> 1, r = y + len - 1 >> 1;
		for (; 0 < l; l >>= 1, r >>= 1) {
			if (lazy[l] == Op::lazy_unit) {
				dat[l] = Op::merge(
					Op::propagate(dat[l << 1], lazy[l << 1], range[l << 1].second - range[l << 1].first),
					Op::propagate(dat[l << 1 | 1], lazy[l << 1 | 1], range[l << 1 | 1].second - range[l << 1 | 1].first));
			}
			if (lazy[r] == Op::lazy_unit) {
				dat[r] = Op::merge(
					Op::propagate(dat[r << 1], lazy[r << 1], range[r << 1].second - range[r << 1].first),
					Op::propagate(dat[r << 1 | 1], lazy[r << 1 | 1], range[r << 1 | 1].second - range[r << 1 | 1].first));
			}
		}
	}
	inline T value(int x, int y) {
		int l = x + len, r = y + len - 1;
		for (int i = hei; 0 < i; --i) {
			evaluate(l >> i);
			evaluate(r >> i);
		}

		T vl = Op::unit, vr = Op::unit;
		for (++r; l < r; l >>= 1, r >>= 1) {
			if (l & 1) {
				vl = Op::merge(vl, Op::propagate(dat[l], lazy[l], range[l].second - range[l].first));
				++l;
			}
			if (r & 1) {
				--r;
				vr = Op::merge(Op::propagate(dat[r], lazy[r], range[r].second - range[r].first), vr);
			}
		}
		return Op::merge(vl, vr);
	}
};
template<class Type, class LazyType> struct node {
	using T = Type;
	using LT = LazyType;
	inline static T unit = 0LL;
	inline static LT lazy_unit = 0LL;
	inline static T merge(T vl, T vr) { return (vl + vr) % MOD; }
	inline static LT lazy_merge(LT vl, LT vr) { return (vl + vr) % MOD;}
	inline static T propagate(T vl, LT vr, int len) { return (vl + vr) % MOD;}
};

int main() {
    init();

    int n, k; cin >> n >> k;
	VI l(n), r(n);
	FOR(i, 0, k) {
		cin >> l[i] >> r[i];
	}
	LazySegmentTree<node<ll, ll>> dp(n);
	dp.update(0, 1, 1);
	FOR(i, 0, n)FOR(j, 0, k) {
		if (i + l[j] < n) {
			dp.update(i + l[j], min(n, i + r[j] + 1), dp.value(i, i + 1));
		}
	}
	print(dp.value(n - 1, n));

    return 0;
}

Measured memory_bytes: 17188