#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#define repeat(i, n) for (int i = 0; (i) < (n); ++(i))
#define repeat_from(i, m, n) for (int i = (m); (i) < (n); ++(i))
using namespace std;
template <class T>
void setmax(T& a, T const& b) {
    if (a < b) a = b;
}

template <class T>
void setmin(T& a, T const& b) {
    if (a > b) a = b;
}

template <typename T, typename X>
auto vectors(T a, X x) { return vector<T>(x, a); }

template <typename T, typename X, typename Y, typename... Zs>
auto vectors(T a, X x, Y y, Zs... zs) {
    auto cont = vectors(a, y, zs...);
    return vector<decltype(cont)>(x, cont);
}

//const int mod = 1000000007;
const int mod = 998244353;
template <typename T, T MOD = 1000000007>
struct Mint {
    static constexpr T mod = MOD;
    T v;
    Mint() : v(0) {}
    Mint(signed v) : v(v) {}
    Mint(long long t) {
        v = t % MOD;
        if (v < 0) v += MOD;
    }

    Mint pow(long long k) {
        Mint res(1), tmp(v);
        while (k) {
            if (k & 1) res *= tmp;
            tmp *= tmp;
            k >>= 1;
        }
        return res;
    }

    static Mint add_identity() { return Mint(0); }
    static Mint mul_identity() { return Mint(1); }

    Mint inv() { return pow(MOD - 2); }

    Mint& operator+=(Mint a) {
        v += a.v;
        if (v >= MOD) v -= MOD;
        return *this;
    }
    Mint& operator-=(Mint a) {
        v += MOD - a.v;
        if (v >= MOD) v -= MOD;
        return *this;
    }
    Mint& operator*=(Mint a) {
        v = 1LL * v * a.v % MOD;
        return *this;
    }
    Mint& operator/=(Mint a) { return (*this) *= a.inv(); }

    Mint operator+(Mint a) const { return Mint(v) += a; }
    Mint operator-(Mint a) const { return Mint(v) -= a; }
    Mint operator*(Mint a) const { return Mint(v) *= a; }
    Mint operator/(Mint a) const { return Mint(v) /= a; }

    Mint operator-() const { return v ? Mint(MOD - v) : Mint(v); }

    bool operator==(const Mint a) const { return v == a.v; }
    bool operator!=(const Mint a) const { return v != a.v; }
    bool operator<(const Mint a) const { return v < a.v; }

    static Mint comb(long long n, int k) {
        Mint num(1), dom(1);
        for (int i = 0; i < k; i++) {
            num *= Mint(n - i);
            dom *= Mint(i + 1);
        }
        return num / dom;
    }
};
template <typename T, T MOD>
constexpr T Mint<T, MOD>::mod;
template <typename T, T MOD>
ostream& operator<<(ostream& os, Mint<T, MOD> m) {
    os << m.v;
    return os;
}
template <typename T, T MOD>
istream& operator>>(istream& os, Mint<T, MOD>& m) {
    os >> m.v;
    return os;
}

// 累積和dp？
// 1 1 1 0 0 1 1 0 0
//
using Int = Mint<long long, mod>;

int main() {
    int N, K;
    cin >> N >> K;
    vector<int> L(K), R(K);
    repeat(i, K) {
        cin >> L[i] >> R[i];
        ++R[i];
    }

    vector<Int> dp(N + 1, Int(0));
    dp[0] = 1LL;
    dp[1] = -1LL;
    //repeat(i, N + 1) cout << dp[i] << " ";
    //cout << endl;
    for (int i = 0; i < N; ++i) {
        if (i > 0) dp[i] += dp[i - 1];
        for (int j = 0; j < K; ++j) {
            if (i + L[j] < N) {
                dp[i + L[j]] += dp[i];
            }
            if (i + R[j] < N) {
                dp[i + R[j]] -= dp[i];
            }
        }
    }
    cout << dp[N - 1] << endl;
    return 0;
}

Measured memory_bytes: 4840