#line 2 "header.hpp"

//%snippet.set('header')%
//%snippet.fold()%
#ifndef HEADER_H
#define HEADER_H

// template version 2.0
using namespace std;
#include <bits/stdc++.h>

// varibable settings
const long long INF = 1e18;
template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = (ll)(a); i < (ll)(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _rrep(i, n) rrepi(i, 0, n)
#define rrepi(i, a, b) for (ll i = (ll)((b)-1); i >= (ll)(a); --i)
#define r_rep(...) _overload3(__VA_ARGS__, rrepi, _rrep, )(__VA_ARGS__)
#define each(i, a) for (auto &&i : a)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(...) make_tuple(__VA_ARGS__)
#define ub upper_bound
#define lb lower_bound
#define lpos(A, x) (lower_bound(all(A), x) - A.begin())
#define upos(A, x) (upper_bound(all(A), x) - A.begin())
template <class T, class U> inline void chmax(T &a, const U &b) { if ((a) < (b)) (a) = (b); }
template <class T, class U> inline void chmin(T &a, const U &b) { if ((a) > (b)) (a) = (b); }
template <typename X, typename T> auto make_table(X x, T a) { return vector<T>(x, a); }
template <typename X, typename Y, typename Z, typename... Zs> auto make_table(X x, Y y, Z z, Zs... zs) { auto cont = make_table(y, z, zs...); return vector<decltype(cont)>(x, cont); }

#define cdiv(a, b) (((a) + (b)-1) / (b))
#define is_in(x, a, b) ((a) <= (x) && (x) < (b))
#define uni(x) sort(all(x)); x.erase(unique(all(x)), x.end())
#define slice(l, r) substr(l, r - l)

typedef long long ll;
typedef long double ld;
using vl = vector<ll>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;

template <typename T>
using PQ = priority_queue<T, vector<T>, greater<T>>;
void check_input() { assert(cin.eof() == 0); int tmp; cin >> tmp; assert(cin.eof() == 1); }

#if defined(PCM) || defined(LOCAL)
#else
#define dump(...) ;
#define dump_1d(...) ;
#define dump_2d(...) ;
#define cerrendl ;
#endif

#endif /* HEADER_H */
//%snippet.end()%
#line 2 "solve.cpp"
template<class T=ll> using vec = vector<T>;
struct Fast { Fast() { std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

ll mod = 998244353;
struct mint {  //{{{
    ll x;
    mint(ll x = 0) : x((x % mod + mod) % mod) {}

    // ?= operator
    mint& operator+=(const mint a) {
        (x += a.x) %= mod;
        return *this;
    }
    mint& operator-=(const mint a) {
        (x += mod - a.x) %= mod;
        return *this;
    }
    mint& operator*=(const mint a) {
        (x *= a.x) %= mod;
        return *this;
    }
    mint& operator/=(const mint& rhs) {
        if (rhs.x == 0) throw runtime_error("mint zero division");
        return *this *= rhs.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 n) const {
        mint res(1), x(*this);
        if (n < 0) {
            n = -n;
            x = (*this).inv();
        }
        while (n) {
            if (n & 1) res *= x;
            x *= x;
            n >>= 1;
        }
        return res;
    }

    mint inv() const {
        if (x == 0) throw runtime_error("inv does not exist");
        return pow(mod - 2);
    }
    // mint inv()const{
    //     int x,y;
    //     int g=extgcd(v,mod,x,y);
    //     assert(g==1);
    //     if(x<0)x+=mod;
    //     return mint(x);
    // }

    bool operator<(const mint& r) const { return x < r.x; }
    bool operator==(const mint& r) const { return x == r.x; }
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }
//}}}

template<class T>/*{{{*/
void pairsort(vector<T>& x, vector<T>& y){
    ll n = sz(x);
    vector<tuple<T, T>> t(n);
    rep(i, n){
        t[i] = make_tuple(x[i], y[i]);
    }
    sort(all(t));
    rep(i, n){
        x[i] = get<0>(t[i]);
        y[i] = get<1>(t[i]);
    }
}
/*}}}*/

int solve() {
    ll n,k;cin>>n>>k;

    vl l(k), r(k);
    rep(i, k){
        cin>>l[i]>>r[i];
    }
    pairsort(l, r);

    vec<mint> dp(n);
    dp[0] = 1;
    dp[1] = -1;

    rep(i, 0, n-1){
        rep(j, k){
            if (i+l[j]<n)   dp[i+l[j]] += dp[i];
            if (i+r[j]+1<n) dp[i+r[j]+1] -= dp[i];
        }
        dp[i+1] += dp[i];
    }
    cout << dp[n-1] << endl;

    return 0; 
}


int main(){/*{{{*/
    solve();
    check_input();
    return 0;
}/*}}}*/


Measured memory_bytes: 4764