#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int(i) = 0; (i) < (n); (i)++)
#define FOR(i, m, n) for(int(i) = (m); (i) < (n); (i)++)
#define All(v) (v).begin(), (v).end()
#define pb push_back
#define MP(a, b) make_pair((a), (b))
template <class T> vector<T> make_vec(size_t a, T val) {
    return vector<T>(a, val);
}
template <class... Ts> auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec(ts...))>(a, make_vec(ts...));
}
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using Graph = vector<vector<int>>;
template <typename T> struct edge {
    int to;
    T cost;
    edge(int t, T c) : to(t), cost(c) {}
};
template <typename T> using WGraph = vector<vector<edge<T>>>;
const int INF = 1 << 30;
const ll LINF = 1LL << 60;
const int MOD = 998244353;

template <uint_fast64_t MOD> class ModInt {
    using u64 = uint_fast64_t;

  public:
    u64 val;

    ModInt(const u64 x = 0) : val((x + MOD) % MOD) {}
    constexpr u64 &value() { return val; }
    constexpr ModInt operator-() { return val ? MOD - val : 0; }
    constexpr ModInt operator+(const ModInt &rhs) const {
        return ModInt(*this) += rhs;
    }
    constexpr ModInt operator-(const ModInt &rhs) const {
        return ModInt(*this) -= rhs;
    }
    constexpr ModInt operator*(const ModInt &rhs) const {
        return ModInt(*this) *= rhs;
    }
    constexpr ModInt operator/(const ModInt &rhs) const {
        return ModInt(*this) /= rhs;
    }
    constexpr ModInt &operator+=(const ModInt &rhs) {
        val += rhs.val;
        if(val >= MOD) {
            val -= MOD;
        }
        return *this;
    }
    constexpr ModInt &operator-=(const ModInt &rhs) {
        if(val < rhs.val) {
            val += MOD;
        }
        val -= rhs.val;
        return *this;
    }
    constexpr ModInt &operator*=(const ModInt &rhs) {
        val = val * rhs.val % MOD;
        return *this;
    }

    constexpr ModInt &operator/=(const ModInt &rhs) {
        *this *= rhs.inv();
        return *this;
    }

    constexpr bool operator==(const ModInt &rhs) {
        return this->val == rhs.val;
    }
    constexpr bool operator!=(const ModInt &rhs) {
        return this->val != rhs.val;
    }
    friend constexpr ostream &operator<<(ostream &os, const ModInt<MOD> &x) {
        return os << x.val;
    }
    friend constexpr istream &operator>>(istream &is, ModInt<MOD> &x) {
        return is >> x.val;
    }

    constexpr ModInt inv() const { return ModInt(*this).pow(MOD - 2); }

    constexpr ModInt pow(ll e) const {
        u64 x = 1, p = val;
        while(e > 0) {
            if(e % 2 == 0) {
                p = (p * p) % MOD;
                e /= 2;
            } else {
                x = (x * p) % MOD;
                e--;
            }
        }
        return ModInt(x);
    }
};

using mint = ModInt<MOD>;

// Range Sum Query by LazySegmentTree
struct LazySegTree {
  private:
    int n;
    vector<mint> node, lazy;

  public:
    LazySegTree(vector<mint> v) {
        int sz = (int)v.size();
        n = 1;
        while(n < sz)
            n *= 2;
        node.resize(2 * n - 1);
        lazy.resize(2 * n - 1, 0);

        for(int i = 0; i < sz; i++)
            node[i + n - 1] = v[i];
        for(int i = n - 2; i >= 0; i--)
            node[i] = node[i * 2 + 1] + node[i * 2 + 2];
    }

    // k番目のノードについて遅延評価
    void eval(int k, int l, int r) {
        // 遅延配列を見て空でなかったら値を伝播
        if(lazy[k] != 0) {
            node[k] += lazy[k];
            // 最下段かどうかチェック
            // 伝播
            if(r - l > 1) {
                lazy[2 * k + 1] += lazy[k] / 2;
                lazy[2 * k + 2] += lazy[k] / 2;
            }
        }

        // 伝播の終了
        lazy[k] = 0;
    }

    mint at(int k) { return getsum(k, k + 1); }

    // [a,b)区間加算
    void add(int a, int b, mint x, int k = 0, int l = 0, int r = -1) {
        if(r < 0)
            r = n;
        // まず評価
        eval(k, l, r);
        // 範囲外なら何もしない
        if(b <= l || r <= a)
            return;

        // 完全に被覆 遅延配列に値を入れ評価
        if(a <= l && r <= b) {
            lazy[k] += mint(r - l) * x;
            eval(k, l, r);
        }
        // そうでないとき 子コードの値を再帰的に計算して計算済みの値をもってくる
        else {
            add(a, b, x, 2 * k + 1, l, (l + r) / 2);
            add(a, b, x, 2 * k + 2, (l + r) / 2, r);
            node[k] = node[2 * k + 1] + node[2 * k] + 2;
        }
    }

    // [a,b)区間取得
    mint getsum(int a, int b, int k = 0, int l = 0, int r = -1) {
        if(r < 0)
            r = n;
        if(b <= l || r <= a)
            return 0;

        // まず評価
        eval(k, l, r);
        if(a <= l && r <= b)
            return node[k];
        mint vl = getsum(a, b, 2 * k + 1, l, (l + r) / 2);
        mint vr = getsum(a, b, 2 * k + 2, (l + r) / 2, r);
        return vl + vr;
    }
};

int main() {
    int N, K;
    cin >> N >> K;
    vector<int> L(K), R(K);
    rep(i, K) cin >> L[i] >> R[i];
    auto dp = make_vec(N + 1, mint(0));
    dp[0] = 1;
    vector<mint> imos(N + 1);
    mint sum = 1;
    for(int i = 0; i < N; i++) {
        sum += imos[i];
        dp[i] = sum;
        for(int j = 0; j < K; j++) {
            imos[min(N, i + L[j])] += dp[i];
            imos[min(N, i + R[j] + 1)] -= dp[i];
        }
    }
    cout << imos[N - 1] << endl;
}

Measured memory_bytes: 6424