#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

// -----------------------------------------------------------------------------------
#define   sz(s)         s.size()
#define   ll            long long int
#define   ull           unsigned ll
#define   ld            long double
#define   print(v)      for(ll i=0;i<v.size();i++)cout<<v[i]<<" "
#define   printpair(v)  for(ll i=0;i<v.size();i++)cout<<v[i].first<<" "<<v[i].second<<"\n"
#define   bmd           1000000007
#define   bmd1          998244353
#define   umll          unordered_map<ll,ll>
#define   mll           map<ll,ll>
#define   mcl           map<char,ll>
#define   pll           pair<ll,ll>
#define   F             first
#define   S             second
#define   setp(x)       setprecision(x)
#define   pb            push_back
#define   all(v)        v.begin(),v.end()
#define   tr(a)         for(auto it=a.begin();it!=a.end();it++)
#define   trr(a)        for(auto it1=a.begin();it1!=a.end();it1++)
#define   vll           vector<long long int>
#define   sorty(v)      sort(v.begin(),v.end())
#define   rsort(v)      sort(v.rbegin(),v.rend())
#define   unik(v)       v.erase(unique(all(v)),v.end())
#define   PI            3.1415926535897932384626
#define   db()          cout<<"\n"<<"here"<<"\n"
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;


//---------------------------------------------------------------------------
const int MOD = bmd1;
const int N=2e5+100;
inline  ll sqr(ll x){return x*x;}
inline  void normal(ll &a) { a = (a+MOD)%MOD; }
inline  ll modMul(ll a, ll b) { a %= MOD, b %= MOD; normal(a), normal(b); return (a*b)%MOD; }
inline  ll modAdd(ll a, ll b) { a %= MOD, b %= MOD; normal(a), normal(b); return (a+b)%MOD; }
inline  ll modSub(ll a, ll b) { a %= MOD, b %= MOD; normal(a), normal(b); a -= b; normal(a); return a; }
inline  ll modPow(ll b, ll p) { ll r = 1;b=b%MOD; while(p) { if(p&1) r = modMul(r, b); b = modMul(b, b); p >>= 1; } return r; }
inline  ll modInv(ll a) { return modPow(a, MOD-2); }
inline  ll modDiv(ll a,ll b) { return modMul(a, modInv(b)); }
//---------------------------------------------------------------------------
void solve()
{
    ll n,k;
    cin>>n>>k;
    vector<pll> vp;
    for(ll i=0;i<k;i++){
        ll l,r;
        cin>>l>>r;
        vp.pb({l,r});
    }
    ll dp[n+5];
    memset(dp,0,sizeof(dp));
    dp[0] = 1;
    dp[1] = 1;
    for(ll i=1;i<=n;i++){
        if(i>2){
            dp[i] = (dp[i]+dp[i-1])%MOD;
        }
        for(auto x:vp){
            ll l = i+x.F;
            ll r = i+x.S;

            if(l<=n)
                dp[l]=(dp[i]+dp[l])%MOD;
            if(r+1<=n){
                dp[r+1]-=dp[i];
                if(dp[r+1]<0)
                    dp[r+1]+=MOD;
                else dp[r+1]%=MOD;
            }

        }
        /*cout << i <<" ";
        for(ll j=1;j<=n;j++)
            cout << dp[j] <<" ";
        cout <<"\n";*/
    }



    cout << (dp[n])%MOD <<"\n";
}
int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    ll t=1;
    //cin>>t;
    while(t--){
        solve();
    }

    return 0;
}


Measured memory_bytes: 5172