#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); ++i)
using namespace std;
using P = pair<int, int>;

template<int64_t MOD> class ModInt {
public:
    int64_t x;
    constexpr ModInt() : x(0) {}
    constexpr ModInt(int64_t v) : x((v % MOD + MOD) % MOD) {}
    constexpr ModInt operator - () const noexcept { return x ? MOD - x : 0;}
    constexpr ModInt operator + (const ModInt a) const noexcept { return ModInt(*this) += a;}
    constexpr ModInt operator - (const ModInt a) const noexcept { return ModInt(*this) -= a;}
    constexpr ModInt operator * (const ModInt a) const noexcept { return ModInt(*this) *= a;}
    constexpr ModInt operator / (const ModInt a) const noexcept { return ModInt(*this) /= a;}
    constexpr ModInt operator / (const int64_t a) const noexcept { return ModInt(*this) /= a;}
    constexpr ModInt operator += (const ModInt a) noexcept {
        x += a.x;
        if (x >= MOD) x -= MOD;
        return *this;
    }
    constexpr ModInt operator += (const int64_t a) noexcept {
        auto hs = ModInt<MOD>(a);
        (*this) += hs;
        return *this;
    }
    constexpr ModInt operator -= (const ModInt a) noexcept {
        if (x < a.x) x += MOD;
        x -= a.x;
        return *this;
    }
    constexpr ModInt operator -= (const int64_t a) noexcept {
        auto hs = ModInt<MOD>(a);
        (*this) -= hs;
        return *this;
    }
    constexpr ModInt operator *= (const ModInt a) noexcept {
        x = x * a.x % MOD;
        return *this;
    }
    constexpr ModInt operator *= (const int64_t a) noexcept {
        auto hs = ModInt<MOD>(a);
        (*this) *= hs;
        return *this;
    }
    constexpr ModInt &operator /= (ModInt a) noexcept {
        int64_t exp = MOD - 2;
        while (exp > 0) {
            if (exp & 1ul) *this *= a;
            a *= a;
            exp >>= 1ul;
        }
        return *this;
    }
    constexpr ModInt &operator /= (int64_t a) noexcept {
        auto hs = ModInt<MOD>(a);
        (*this) /= hs;
        return *this;
    }
    constexpr ModInt &operator ++ () noexcept {
        return *this;
    }
    constexpr ModInt operator ++ (int) noexcept {
        if (++x >= MOD) x -= MOD;
        return *this;
    }
    constexpr ModInt &operator -- () noexcept {
        return *this;
    }
    constexpr ModInt operator -- (int) noexcept {
        if (x-- == 0) x += MOD;
        return *this;
    }
    constexpr bool operator < (const ModInt a) const noexcept { return x < a.x;}
    constexpr bool operator == (const ModInt a) const noexcept { return this->x == a.x;}
    constexpr bool operator != (const ModInt a) const noexcept { return !(*this == a);}
    friend istream &operator >> (istream &in, ModInt &m) {
        in >> m.x;
        if (m.x < 0) m.x += MOD;
        m.x %= MOD;
        return in;
    }
    friend ostream &operator << (ostream &out, const ModInt &p) { return out << p.x;}
    constexpr ModInt pow(int64_t p) const {
        ModInt ret(1);
        ModInt mul(x);
        while (p > 0) {
            if (p & 1ul) ret *= mul;
            mul *= mul;
            p >>= 1ul;
        }
        return ret;
    }
};

const int64_t MOD = 998244353LL;
using mint = ModInt<MOD>;

template<class T = int> struct Segtree {
using Func = function<T(T, T)>;
private:
    int n = 1;
    T def;
    vector<T> node;
    const Func f;
public:
    Segtree(int sz, T _def, Func _f) : def(_def), f(_f) {
        while (n < sz) n *= 2;
        node.resize(2 * n - 1, def);
    }
    void update(int x, T val) {
        x += n - 1;
        node[x] = val;
        while (x > 0) {
            x = (x - 1) / 2;
            node[x] = f(node[2 * x + 1], node[2 * x + 2]);
        }
    }
    T query(int a, int b, int k = 0, int l = 0, int r = -1) {
        if (r < 0) r = n;
        if (r <= a || b <= l) return def;
        if (a <= l && r <= b) return node[k];
        T vl = query(a, b, 2 * k + 1, l, (l + r) / 2);
        T vr = query(a, b, 2 * k + 2, (l + r) / 2, r);
        return f(vl, vr);
    }
};

void solve() {
    int N, K;
    cin >> N >> K;
    vector<int> L(K), R(K);
    rep(i, K) cin >> L[i] >> R[i];
    vector<P> LR(K);
    rep(i, K) LR[i] = make_pair(L[i], R[i]);
    Segtree<mint> dp(N, 0, [](mint a, mint b) { return a + b; });
    dp.update(0, 1);
    for(int j = 1; j < N; ++j) {
        rep(i, K) {
            auto[l, r] = LR[i];
            auto tmp = dp.query(j, j + 1);
            dp.update(j, tmp + dp.query(max(0, j - r), max(0, j - l + 1)));
        }
    }
    cout << dp.query(N - 1, N) << '\n';
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
}


Measured memory_bytes: 7432