#include <bits/stdc++.h>
using namespace std;

#define REP(i,m,n) for(int i=(m); i<(int)(n); i++)
#define RREP(i,m,n) for(int i=(int)((n)-1); i>=m; i--)
#define rep(i,n) REP(i,0,n)
#define rrep(i,n) RREP(i,0,n)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define fi first
#define se second
#define debug(...) {cerr<<"[L"<<__LINE__<<"] "; _debug(__VA_ARGS__);}

template<typename T>
string join(const vector<T>&v, string del=", "){ stringstream s;
    for(auto x : v) s << del << x; return s.str().substr(del.size());
}
template<typename T>
ostream& operator<<(ostream& o, const vector<T>&v){
    if(v.size()) o << "[" << join(v) << "]"; return o;
}
template<typename T>
ostream& operator<<(ostream& o, const vector<vector<T> >&vv){
    int l = vv.size();
    if(l){ o<<endl; rep(i,l) o << (i==0 ? "[ " : ",\n  " ) << vv[i] << (i==l-1 ? " ]" : ""); }
    return o;
}
template<typename T1, typename T2>
ostream& operator<<(ostream& o, const pair<T1, T2>& p){
    return o << "(" << p.first << ", " << p.second << ")";
}
inline void _debug(){cerr<<endl;}
template<class First, class... Rest>
void _debug(const First& first, const Rest&... rest){cerr<<first<<" ";_debug(rest...);}

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;

const double PI = (1*acos(0.0));
const double EPS = 1e-9;
const int INF = 0x3f3f3f3f;
const ll INFL = 0x3f3f3f3f3f3f3f3fLL;
const ll mod = 998244353;

inline void finput(string filename) {
    freopen(filename.c_str(), "r", stdin);
}

struct mint {
    long long x;
    mint(long long 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;
    }
    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;
    }
    friend ostream& operator<<(ostream& os, const mint& m){
        os << m.x; return os;
    }
};

template<typename T>
struct BIT{
    int n;
    vector<T> dat;
    BIT(int n) : n(n), dat(n+1,0){}
    void add(int x, T val){
        for(int i = x+1; i <= n; i += (i & -i)) dat[i] += val;
    }
    T sum(int x){
        T ret = 0;
        for(int i = x+1; i > 0; i -= (i & -i)) ret += dat[i];
        return ret;
    }
    T sum(int a, int b){
        return sum(b) - sum(a-1);
    }
};


int main(){
    ios_base::sync_with_stdio(0);
    // finput("./input");
    int n,k; cin >> n >> k;
    vector<pii> s;
    rep(i,k){
        int l,r; cin >> l >> r;
        s.emplace_back(l,r);
    }

    BIT<mint> dp(n+1);
    dp.add(0, 1);
    dp.add(1, -1);
    rep(i,n){
        for(auto p : s){
            int l = p.fi, r = p.se;
            mint d = dp.sum(i);
            dp.add(i+l, d);
            dp.add(min(i+r+1, n), -d);
        }
    }
    cout << dp.sum(n-1) << endl;
    return 0;
}

Measured memory_bytes: 4844