#define _DEBUG
//ヘッダー
#include<bits/stdc++.h>
using namespace std;

//型定義
typedef long long ll;

//定数
const ll INF=1e+18;
const int MOD=998244353;

//デバッグ
#define CHOOSE(a) CHOOSE2 a
#define CHOOSE2(a0,a1,a2,a3,a4,x,...) x
#define debug1(x1) cout<<#x1<<": "<<x1<<endl
#define debug2(x1,x2) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<endl
#define debug3(x1,x2,x3) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<endl
#define debug4(x1,x2,x3,x4) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<endl
#define debug5(x1,x2,x3,x4,x5) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<", "#x5<<": "<<x5<<endl
#ifdef _DEBUG
#define debug(...) CHOOSE((__VA_ARGS__,debug5,debug4,debug3,debug2,debug1,~))(__VA_ARGS__)
#else
#define debug(...)
#endif

//REPマクロ
#define REP(i,n) for(ll i=0;i<(ll)(n);i++)
#define REPD(i,n) for(ll i=n-1;i>=0;i--)
#define REP2(i,a,b) for(ll i=a;i<(ll)(b);i++)
#define REPD2(i,a,b) for(ll i=a;i>(ll)(b);i--)

// 多次元 vector 生成
template<class T>
vector<T> make_vec(size_t a){
    return vector<T>(a);
}
template<class T, class... Ts>
auto make_vec(size_t a, Ts... ts){
  return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}

//vectorの扱い
#define ALL(x) (x).begin(),(x).end() //sortなどの引数省略
#define SIZE(x) ((ll)(x).size()) //size
#define MAX(x) *max_element(ALL(x)) //最大値
#define MIN(x) *min_element(ALL(x)) //最小値

//省略
using vi  = vector<int>;
using vii = vector<vector<int>>;
using vl  = vector<ll>;
using vll = vector<vector<ll>>;
using pii = pair<int,int>;
using pll = pair<ll,ll>;

//区間加算・区間和遅延評価セグメント木
//クエリlog(N)
//LazySegmentTree seg(vl(N+10,0));で初期化
//seg.getsum(a,b);でインデックスa～b-1までの区間和を計算
//seg.add(a,b,x);でインデックスa～b-1までの値にxを加算
struct LazySegmentTree {
private:
    int n;
    vector<ll> node, lazy;

public:
    LazySegmentTree(vector<ll> v) {
        int sz = (int)v.size();
        n = 1; while(n < sz) n *= 2;
        node.resize(2*n-1);
        lazy.resize(2*n-1, 0);

        for(int i=0; i<sz; i++) node[i+n-1] = v[i];
        for(int i=n-2; i>=0; i--) node[i] = node[i*2+1] + node[i*2+2];
    }

    void eval(int k, int l, int r) {
        if(lazy[k] != 0) {
            node[k] += lazy[k];
            if(r - l > 1) {
                lazy[2*k+1] += lazy[k] / 2;
                lazy[2*k+2] += lazy[k] / 2;
            }
            lazy[k] = 0;
        }
    }

    void add(int a, int b, ll x, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        eval(k, l, r);
        if(b <= l || r <= a) return;
        if(a <= l && r <= b) {
            lazy[k] += (r - l) * x;
            eval(k, l, r);
        }
        else {
            add(a, b, x, 2*k+1, l, (l+r)/2);
            add(a, b, x, 2*k+2, (l+r)/2, r);
            node[k] = (node[2*k+1] + node[2*k+2])%MOD;
        }
    }

    ll getsum(int a, int b, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        eval(k, l, r);
        if(b <= l || r <= a) return 0;
        if(a <= l && r <= b) return node[k];
        ll vl = getsum(a, b, 2*k+1, l, (l+r)/2);
        ll vr = getsum(a, b, 2*k+2, (l+r)/2, r);
        return (vl + vr)%MOD;
    }
};

int main(){
    ll N,K;
    cin>>N>>K;
    vector<pll> LR(K);
    REP(i,K){
        ll l,r;
        cin>>l>>r;
        LR[i].first=l;
        LR[i].second=r;   
    }

    //LazySegmentTree seg(vl(N+10,0));で初期化
    //seg.getsum(a,b);でインデックスa～b-1までの区間和を計算
    //seg.add(a,b,x);でインデックスa～b-1までの値にxを加算
    LazySegmentTree seg(vl(600000,0));
    seg.add(1,2,1);
    REP2(i,1,N+1){
        ll val=seg.getsum(i,i+1);
        REP(j,K){
            ll l=LR[j].first;
            ll r=LR[j].second;
            seg.add(i+l,i+r+1,val);
        }
    }

    cout<<seg.getsum(N,N+1)%MOD<<endl;

}

Measured memory_bytes: 40752