// ######      ###      #######    #######    ##     #     #####        ###     ##### //
// #     #    #   #          #        #       # #    #    #     #      #   #     ###  //
// #     #   #     #        #         #       #  #   #   #       #    #     #    ###  //
// ######   #########      #          #       #   #  #   #           #########    #   //
// #     #  #       #     #           #       #    # #   #    ####   #       #    #   //
// #     #  #       #    #            #       #     ##   #    #  #   #       #        //
// ######   #       #   #######    #######    #      #    #####  #   #       #    #   //

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("avx,avx2,fma")
#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;
typedef vector<ll> vl;
typedef vector<vector<ll>> vvl;
typedef pair<ll, ll> ppl;
#define ain(a,n) for(ll i=0;i<(n);++i)  cin>>(a)[i];
#define DEBUG(x) cout << '>' << #x << ':' << x << endl;
#define loop(i,n) for(ll i=0;i<(n);++i)
#define FOR(i,a,b) for(ll i=(a);i<=(b);++i)
#define FORD(i,a,b) for(ll i=(a);i>=(b);--i)
#define cases ll T=0;cin>>T;while(T--)
#define ff first
#define ss second
#define all(v) v.begin(),v.end()
#define END "\n"
#define pb push_back
#define mp make_pair
#define go(c,itr) for(auto itr=(c).begin(); itr!=(c).end(); ++itr)
// #define back(c,itr) for(auto itr=(c).rbegin(); itr!=(c).rend(); ++itr)
#define PI 3.14159265359
#define inf 9e18
#define MOD 1000000007
#define MODU 998244353
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define MAXN 300005
#define BLOCK 555
const string alpha = "abcdefghijklmnopqrstuvwxyz";
const ll N = 200005;
const long double epsilon = 1e-9;
inline ll myceil(ll a, ll  b) {
    return (ceil(1.0 * a / b * 1.0));
}
ll binexp(ll a, ll b, ll m) {
    a %= m;
    ll res = 1;
    while (b > 0) {
        if (b & 1)
            res = res * a % m;
        a = a * a % m;
        b >>= 1;
    }
    return res;
}
ll modinvfermat(ll a, ll m)
{
    return binexp(a, m - 2, m);
}
void task(bool flag)
{
    if (flag)
        cout << "YES\n";
    else
        cout << "NO\n";
}
ll lcm(ll a, ll b)
{
    return ((1LL * a * b) / (__gcd(a, b)));
}


signed main() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    fast
    ll n, k;
    cin >> n >> k;
    vector<ppl> range(k);
    loop(i, k)   cin >> range[i].ff >> range[i].ss;

    vl dp(n + 1, 0), pref(n + 1, 0);
    pref[1] = 1 , pref[2] = -1;
    FOR(i, 1, n)
    {
        (pref[i] += pref[i - 1] + dp[i]) %= MODU;
        (pref[i] += MODU) %= MODU;
        loop(j, k)
        {
            if (i + range[j].ff <= n)
                (dp[i + range[j].ff] += pref[i]) %= MODU;
            if (i + range[j].ss + 1 <= n)
            {
                (dp[i + range[j].ss + 1] -= pref[i]) %= MODU;
                (dp[i + range[j].ss + 1] += MODU) %= MODU;
            }
        }
    }

    cout << pref[n] << END;

#ifndef ONLINE_JUDGE
    cout << "\nTime Elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " sec\n";
#endif
    return 0;
}



Measured memory_bytes: 6352