#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 998244353;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

template <u32 M>
struct modint {
    u32 val;
public:
    static modint raw(int v) { modint x; x.val = v; return x; }
    modint() : val(0) {}
    template <class T>
    modint(T v) { ll x = (ll)(v%(ll)(M)); if (x < 0) x += M; val = u32(x); }
    modint(bool v) { val = ((unsigned int)(v) % M); }
    modint& operator++() { val++; if (val == M) val = 0; return *this; }
    modint& operator--() { if (val == 0) val = M; val--; return *this; }
    modint operator++(int) { modint result = *this; ++*this; return result; }
    modint operator--(int) { modint result = *this; --*this; return result; }
    modint& operator+=(const modint& b) { val += b.val; if (val >= M) val -= M; return *this; }
    modint& operator-=(const modint& b) { val -= b.val; if (val >= M) val += M; return *this; }
    modint& operator*=(const modint& b) { u64 z = val; z *= b.val; val = (u32)(z % M); return *this; }
    modint& operator/=(const modint& b) { return *this = *this * b.inv(); }
    modint operator+() const { return *this; }
    modint operator-() const { return modint() - *this; }
    modint pow(long long n) const { modint x = *this, r = 1; while (n) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
    modint inv() const { return pow(M-2); }
    friend modint operator+(const modint& a, const modint& b) { return modint(a) += b; }
    friend modint operator-(const modint& a, const modint& b) { return modint(a) -= b; }
    friend modint operator*(const modint& a, const modint& b) { return modint(a) *= b; }
    friend modint operator/(const modint& a, const modint& b) { return modint(a) /= b; }
    friend bool operator==(const modint& a, const modint& b) { return a.val == b.val; }
    friend bool operator!=(const modint& a, const modint& b) { return a.val != b.val; }
};
using mint = modint<MOD>;

template <class M>
struct DualSegmentTree{
    using T = typename M::T;
    int sz, height{};
    vector<T> lazy;
    explicit DualSegmentTree(int n) {
        sz = 1; while(sz < n) sz <<= 1, height++;
        lazy.assign(2*sz, M::e());
    }

    void eval(int k){
        if(lazy[k] == M::e()) return;
        lazy[(k<<1)|0] = M::f(lazy[(k<<1)|0], lazy[k]);
        lazy[(k<<1)|1] = M::f(lazy[(k<<1)|1], lazy[k]);
        lazy[k] = M::e();
    }
    void thrust(int k){ for (int i = height; i; --i) eval(k>>i); }
    void update(int a, int b, const T &x){
        thrust(a += sz); thrust(b += sz-1);
        for (int l = a, r = b+1;l < r; l >>=1, r >>= 1) {
            if(l&1) lazy[l] = M::f(lazy[l], x), l++;
            if(r&1) --r, lazy[r] = M::f(lazy[r], x);
        }
    }

    T operator[](int k){
        thrust(k += sz);
        return lazy[k];
    }
};

struct Monoid{
    using T = mint;
    static T f(T a, T b) { return a+b; }
    static T e() { return 0; }
};


int main() {
    int n, k;
    cin >> n >> k;
    vector<int> ls(k), rs(k);
    for (int i = 0; i < k; ++i) {
        cin >> ls[i] >> rs[i];
        rs[i]++;
    }
    DualSegmentTree<Monoid> seg(n);
    seg.update(0, 1, 1);
    for (int i = 0; i < n; ++i) {
        mint val = seg[i];
        for (int j = 0; j < k; ++j) {
            if(i+ls[j] >= n) continue;
            int l = i+ls[j], r = min(n, i+rs[j]);
            seg.update(l, r, val);
        }
    }
    cout << seg[n-1].val << "\n";
    return 0;
}

Measured memory_bytes: 5368