#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#define DEBUG
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) {
            os << ',';
        }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]:", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
const double EPS = 1e-7;
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 998244353;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

//-------------------------------------

template <typename Monoid> struct SegmentTree {
    using F = function<Monoid(Monoid, Monoid)>;

  private:
    int n;
    vector<Monoid> node;
    Monoid E;
    F f;

  public:
    SegmentTree(vector<Monoid> v, Monoid e, const F func) : f(func), E(e) {
        int sz = v.size();
        n = 1;
        while(n < sz) {
            n *= 2;
        }
        node.resize(2 * n - 1, E);
        for(int i = 0; i < sz; i++) {
            node[i + n - 1] = v[i];
        }
        for(int i = n - 2; i >= 0; i--) {
            node[i] = f(node[2 * i + 1], node[2 * i + 2]);
        }
    }

    void update(int i, Monoid val) {
        i += (n - 1);
        node[i] = val;
        while(i > 0) {
            i = (i - 1) / 2;
            node[i] = f(node[2 * i + 1], node[2 * i + 2]);
        }
    }

    Monoid query(int a, int b, int i = 0, int l = 0, int r = -1) {
        if(r < 0) {
            r = n;
        }
        if(r <= a || b <= l) {
            return E;
        }
        if(a <= l && r <= b) {
            return node[i];
        }
        Monoid vl = query(a, b, 2 * i + 1, l, (l + r) / 2);
        Monoid vr = query(a, b, 2 * i + 2, (l + r) / 2, r);
        return f(vl, vr);
    }

    Monoid operator[](const int &i) const { return node[i + n - 1]; }
};

template <int mod> struct ModInt {
    int x;

    ModInt() : x(0) {}

    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    ModInt &operator+=(const ModInt &p) {
        if((x += p.x) >= mod)
            x -= mod;
        return *this;
    }

    ModInt &operator-=(const ModInt &p) {
        if((x += mod - p.x) >= mod)
            x -= mod;
        return *this;
    }

    ModInt &operator*=(const ModInt &p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }

    ModInt &operator/=(const ModInt &p) {
        *this *= p.inverse();
        return *this;
    }

    ModInt operator-() const { return ModInt(-x); }

    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

    bool operator==(const ModInt &p) const { return x == p.x; }

    bool operator!=(const ModInt &p) const { return x != p.x; }

    ModInt inverse() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while(b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
        }
        return ModInt(u);
    }

    ModInt pow(int64_t n) const {
        ModInt ret(1), mul(x);
        while(n > 0) {
            if(n & 1)
                ret *= mul;
            mul *= mul;
            n >>= 1;
        }
        return ret;
    }

    friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }

    friend istream &operator>>(istream &is, ModInt &a) {
        int64_t t;
        is >> t;
        a = ModInt<mod>(t);
        return (is);
    }

    static int get_mod() { return mod; }
};

using mint = ModInt<MOD>;

int main() {
    int n, k;
    cin >> n >> k;
    vector<pair<int, int>> s(k);
    for(int i = 0; i < k; i++) {
        cin >> s[i].first >> s[i].second;
    }
    auto op = [](mint a, mint b) { return a + b; };
    SegmentTree<mint> dp(vector<mint>(n + 1, 0), 0, op);
    dp.update(1, 1);
    for(int i = 1; i <= n; i++) {
        for(auto lr : s) {
            if(i - lr.first <= 0) {
                continue;
            }
            int L = max(1, i - lr.second);
            int R = max(1, i - lr.first) + 1;
            if(L >= R) {
                continue;
            }
            dp.update(i, dp[i] + dp.query(L, R));
        }
    }
    cout << dp[n] << endl;
}

Measured memory_bytes: 6108