#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (ll i = 0; i < n; ++ i)
using ll = long long ;
using vi = vector<ll>;
using vb = vector<bool>;
using vvi = vector<vi>;
const ll mod = 998244353;
//----------------------------------------------------------------
const ll si_f = 5e5;
ll f[si_f+1], invf[si_f+1], inv[si_f+1];
ll po(ll n,ll m){
    ll res = 1;
    while (m) {
        if (m&1) res = res * n % mod;
        n = n * n % mod;
        m /= 2;
    }
    return res;
}
void init() {
    f[0] = f[1] = 1;
	invf[0] = invf[1] = 1;
	inv[1] = 1;
    for(ll i = 2; i < si_f; ++i){
		f[i] = f[i-1] * i % mod;
		inv[i] = mod - inv[mod%i] * (mod/i) % mod;
		invf[i] = invf[i-1] * inv[i] % mod;
	}
	return;
}
ll C(int n, int k) {
    ll a = f[n]; // = n!
    ll b = invf[n-k]; // = (n-k)!
    ll c = invf[k]; // = k!

    ll bc = (b * c) % mod;
  
    return (a * bc) % mod;
}
//----------------------------------------------------------------
void solver(ll x,ll &res,ll id){
	if(x%2==0){
		ll y = x/2;
		ll c = C(x,y) * po(y+1,mod-2) % mod;
		res = res * c % mod;
	} else if(id == 0){
		ll y = x/2;
		ll c = 2 * C(x,y) * po(y+2,mod-2) % mod;
		res = res * c % mod;
	} else res = 0;
	return;
}
//----------------------------------------------------------------
int main(){
	init();
    int N,Q;
	cin >> N >> Q;
	vi imos(N+1,0),L(Q),R(Q);
	rep(i,Q){
		cin >> L[i] >> R[i];
		--L[i];
		imos[L[i]] += (1<<i);
		imos[R[i]] -= (1<<i);
		R[i] -= L[i];
	}
	rep(i,N) imos[i+1] += imos[i];
	map<ll,ll> kukan;
	rep(i,N) ++kukan[imos[i]];
	ll res = f[N/2]*f[(N+1)/2] % mod;
	for(auto siz:kukan){
		solver(siz.second,res,siz.first);
	}
	cout << res << endl;
}