#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <string>

#define rep(i, a, b) for ( int i = (a); i < (b); i++ )
#define per(i, a, b) for ( int i = (b)-1; i >= (a); i--)
#define pb push_back
#define mp make_pair
#define bg begin()
#define en end()
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define sz(v) (int)(v).size()

using namespace std;

typedef long long ll;
typedef long double ld;

using P = pair<int, int>;
template<typename T>
struct Edge {
    int u, v;
    T cost;
    Edge(int u, int v, T c) : u(u), v(v), cost(c) {}
    bool operator< (const Edge &e) const {return cost < e.cost;}
};

static const long long mod = 998244353;
static const long long LINF = (ll)(1e18+99);
static const int INF = 1e9+99;

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 >;

ll ans;
mint dp[200005];
mint S[200005];
vector<int> L, R;

int main(void) {
    int n, k;
    cin >> n >> k;
    vector<int> v;
    rep(i, 0, k) {
        int l, r;
        cin >> l >> r;
        L.pb(l);
        R.pb(r);
    }

    dp[1] = 1;
    S[1] = 1;
    rep(i, 2, n+1) {
        rep(j, 0, k) {
            int l = i-R[j], r = i-L[j];
            if (r<1) continue;
            mint x = S[r] - S[max(0, l-1)];
            dp[i] += x;
        }
        S[i] += S[i-1] + dp[i];
    }

    
    cout << dp[n] << endl;
    return 0;
}





Measured memory_bytes: 5200