#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define endl '\n'
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))

using namespace std;

const ll mod=998244353;

struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
 
  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
// combination mod prime
// https://www.youtube.com/watch?v=8uowVvQ_-Mo&feature=youtu.be&t=1619
struct combination {
  vector<mint> fact, ifact;
  combination(ll n):fact(n+1),ifact(n+1) {
    assert(n < mod);
    fact[0] = 1;
    for (ll i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (ll i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(ll n, ll k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
  mint p(ll n, ll k) {
    return fact[n]*ifact[n-k];
  }
};

struct LazySegmentTree{
private:
    ll n;
    vector<ll> node, lazy;
public:
    LazySegmentTree(vector<ll> v){
        ll sz=(ll)v.size();
        n=1;
        while(n<sz) n*=2;
        node.resize(2*n-1);
        lazy.resize(2*n-1,0);
        rep(i,sz) node[i+n-1]=v[i];
        for(ll i=n-2;i>=0;i--) node[i]=(node[2*i+1]+node[2*i+2])%mod;
    }
    void eval(ll k,ll l,ll r){
        if(lazy[k]!=0){
            node[k]+=lazy[k];
            node[k]%=mod;
            if(r-l>1){
                lazy[2*k+1]+=lazy[k]/2;
                lazy[2*k+2]+=lazy[k]/2;
                lazy[2*k+1]%=mod;
                lazy[2*k+2]%=mod;
            }
            lazy[k]=0;
        }
    }
    void add(ll a,ll b,ll x,ll k=0,ll l=0,ll 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)%mod;
            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(ll a,ll b,ll k=0,ll l=0,ll r=-1){
        if(r<0) r=n;
        if(b<=l || r<=a) return 0;
        eval(k,l,r);
        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<ll> l(k),r(k);
    vector<ll> sum(n+1); //1~N
    
    LazySegmentTree seg=LazySegmentTree(sum);
    rep(i,k){
        cin >> l[i] >> r[i];
        //seg.add(l[i],r[i]+1,1);
    }
    seg.add(0,1,1);
    for(ll i=1;i<=n;i++){
        ll tot=0;
        rep(j,k){
            ll L=max(0LL,i-r[j]);
            ll R=max(0LL,i-l[j]);
            //if(i==4) cout << L << " " << R << endl;
            if(i-l[j]<0) continue;
            tot+=seg.getsum(L,R+1);
            tot%=mod;
        }
        
        seg.add(i,i+1,tot);
        //cout << i << " " << seg.getsum(i,i+1) << endl;
    }
    
    cout << seg.getsum(n-1,n) << endl;
    return 0;
}

Measured memory_bytes: 14596