#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef pair<ll, ll> PP;
#define rep(i, n) for(ll i = 0; i < ll(n); i++)
#define rrep(i, n) for(ll i = n - 1; i > -1; i--)
#define all(v) v.begin(), v.end()
#define pb push_back
#define fi first
#define se second
template <class X> void print(X x) { cout << x << endl; }
#define in(A, n)                                                                                                       \
    rep(i, n) {                                                                                                        \
        cin >> f;                                                                                                      \
        A.push_back(f);                                                                                                \
    }

void print(vl x) {
    for(ll i : x) {
        cout << i << " ";
    }
    cout << endl;
}
const ll INF = (1LL << 61) - 1;
const ll MOD = 998244353;
const ll MAX_N = 500010;
ll a, b, c, d, e, f, h, x, y, z, p, q, n, t, r, k, w, l, ans, i, j, u, v, m;
ll codeforces = 1;
string S, T;
vector<vl> g(MAX_N);
vl A, B;
#include <cstdint>
template <std::uint_fast64_t Modulus> class modint {
    using u64 = std::uint_fast64_t;

  public:
    u64 a;
    constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
    constexpr u64 &value() noexcept { return a; }
    constexpr const u64 &value() const noexcept { return a; }
    constexpr modint operator+(const modint rhs) const noexcept { return modint(*this) += rhs; }
    constexpr modint operator-(const modint rhs) const noexcept { return modint(*this) -= rhs; }
    constexpr modint operator*(const modint rhs) const noexcept { return modint(*this) *= rhs; }
    constexpr modint operator/(const modint rhs) const noexcept { return modint(*this) /= rhs; }
    constexpr modint &operator+=(const modint rhs) noexcept {
        a += rhs.a;
        if(a >= Modulus) {
            a -= Modulus;
        }
        return *this;
    }
    constexpr modint &operator-=(const modint rhs) noexcept {
        if(a < rhs.a) {
            a += Modulus;
        }
        a -= rhs.a;
        return *this;
    }
    constexpr modint &operator*=(const modint rhs) noexcept {
        a = a * rhs.a % Modulus;
        return *this;
    }
    constexpr modint &operator/=(modint rhs) noexcept {
        u64 exp = Modulus - 2;
        while(exp) {
            if(exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        return *this;
    }
};
using mint = modint<MOD>;
void input() {
    cin >> n >> l;
    rep(i, l) {
        cin >> x >> y;
        A.pb(x);
        B.pb(y);
    }
}
void solve() {
    vector<mint> ruiseki;
    ruiseki.pb(0);
    ruiseki.pb(1);
    rep(i, n) {
        mint k = 0;
        rep(j, l) {
            a = A[j];
            b = B[j];
            p = i + 2 - a;
            q = i + 1 - b;
            k += ruiseki[max(0LL, p)] - ruiseki[max(0LL, q)];
        }
        ruiseki.pb(ruiseki.back() + k);
    }

    print((ruiseki[n] - ruiseki[n - 1]).a);
}
int main() {
    // cout<<fixed<<setprecision(15);
    cin.tie(0);
    ios::sync_with_stdio(false);
    input();
    while(codeforces--) {
        solve();
    }
}

Measured memory_bytes: 17012