#include <iostream>
#include <sstream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <memory>
#include <complex>
#include <numeric>
#include <cstdio>
#include <iomanip>
#include <random>

#define REP(i,m,n) for(int i=int(m);i<int(n);i++)
#define RREP(i,m,n) for(int i=int(n)-1;i>=int(m);--i)
#define EACH(i,c) for (auto &(i): c)
#define all(c) begin(c),end(c)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort(begin(c),end(c))
#define pb emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
//#define int long long

#ifdef LOCAL
#define DEBUG(s) cout << (s) << endl
#define dump(x)  cerr << #x << " = " << (x) << endl
#define BR cout << endl;
#else
#define DEBUG(s) do{}while(0)
#define dump(x) do{}while(0)
#define BR 
#endif
using namespace std;

using UI = unsigned int;
using UL = unsigned long;
using LL = long long;
using ULL = unsigned long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VLL = vector<LL>;
using VVLL = vector<VLL>;
using VS = vector<string>;
using PII = pair<int,int>;
using VP = vector<PII>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

// constexpr double EPS = 1e-10;
//constexpr double PI  = acos(-1.0);
//constexpr int INF = INT_MAX;
constexpr int MOD = 998244353;
//inline void modAdd(LL &l, LL &r) {l = (l + r) % MOD;}

// auto mod int
struct mint {
    LL x;
    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(const 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;
    }
    LL operator()() const {
        return x;
    }
};
using VM = vector<mint>;
using VVM = vector<VM>;

// 1-indexed
template <typename T=int>
struct BIT {
    vector<T> v;
    const int n;

    BIT(int n): n(n), v(n+1,0) {}

    void add(int i, T x) {
        i += 1;
        while (i <= n) {
            v[i] += x;
            i += i & -i;
        }
    }
    T sum(int i) {
        i += 1;
        T ret = 0;
        while (i > 0) {
            ret += v[i];
            i -= i & -i;
        }
        return ret;
    }
    T sum(int l, int r) {
        // dump(l);
        // dump(r);
        return sum(r) - sum(l-1);
    }
};

void solve() {
    int n,k;
    cin >> n >> k;
    VI l(k),r(k);
    REP(i,0,k) {
        cin >> l[i] >> r[i];
    }
    BIT<mint> bit(n);
    bit.add(0,1);
    REP(i,1,n) {
        // dump(i);
        mint sum = 0;
        REP(j,0,k) {
            // dump(j);
            if (i - l[j] < 0) continue;
            sum += bit.sum(max(0,i-r[j]),i-l[j]);
        }
        // dump(sum());
        bit.add(i,sum);
    }
    cout << bit.sum(n-1,n-1)() << endl;
    // REP(i,0,n+1) dump(bit.v[i]());
}

signed main() {
    solve();
    
    return 0;
}

Measured memory_bytes: 4840