// Problem: No.2605 Pickup Parentheses
// Contest: yukicoder
// URL: https://yukicoder.me/problems/no/2605
// Memory Limit: 512 MB
// Time Limit: 2000 ms

#include<bits/stdc++.h>
#define debug(x) cerr<<(#x)<<" "<<(x)<<endl
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
#define pii pair<ll,ll>
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define per(i,a,b) for(ll i=(a);i>=(b);--i)
using namespace std;
bool Mbe; 
ll read(){
	ll x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
	return x*f;
}
void write(ll x){
	if(x<0)putchar('-'),x=-x;
	if(x>9)write(x/10);
	putchar(x%10+'0');
}
const ll N=2e6+9,Mod=998244353,G=3,IG=332748118;
ll n,m,a[N],fac[N],ifac[N],r[N],cat[N];
ll pw(ll x,ll p){
	ll res=1;
	while(p){
		if(p&1)res=res*x%Mod;
		x=x*x%Mod;
		p>>=1;
	}
	return res;
}
void NTT(vector<ll>&a,ll n,ll sgn){
	rep(i,0,n-1){
		if(i<r[i])swap(a[i],a[r[i]]);
	}
	for(ll mid=1;mid<n;mid*=2){
		ll Wn=pw(sgn==1?G:IG,(Mod-1)/(mid<<1));
		for(ll R=mid<<1,j=0;j<n;j+=R){
			ll w=1;
			for(ll k=0;k<mid;k++,w=w*Wn%Mod){
				ll x=a[j+k],y=a[j+k+mid]*w%Mod;
				a[j+k]=(x+y)%Mod,a[j+k+mid]=(x-y+Mod)%Mod;
			}
		}
	}
	if(sgn==-1){
        ll inv=pw(n,Mod-2);
        rep(i,0,n-1)a[i]=a[i]*inv%Mod;
    }
}
void MUL(vector<ll>&f,vector<ll>g,ll n,ll m){
	ll mxlen=n+m;
	ll p=1,c=0;
	while(p<=mxlen)p<<=1,c++;
	f.resize(p),g.resize(p);
	r[0]=0;
	rep(i,1,p-1)r[i]=(r[i>>1]>>1)|((i&1)<<(c-1));
	NTT(f,p,1),NTT(g,p,1);
	rep(i,0,p-1)f[i]=f[i]*g[i]%Mod;
	NTT(f,p,-1);
	f.resize(n+m-1);
}
vector<ll> work(ll l,ll r){
	if(l==r){
		vector<ll>vec(a[l]+1,0);
		vec[0]=1,vec[a[l]]=Mod-cat[a[l]/2];
		return vec;
	}
	ll mid=(l+r)>>1;
	vector<ll>lf=work(l,mid);
	vector<ll>rg=work(mid+1,r);
	MUL(lf,rg,(ll)lf.size(),(ll)rg.size());
	return lf;
}
bool Med;
int main(){
	cerr<<fabs(&Med-&Mbe)/1048576.0<<"MB\n";
	n=read(),m=read();
	rep(i,1,m){
		ll l=read(),r=read();
		a[i]=r-l+1;
	}
	fac[0]=1;
	rep(i,1,n*2)fac[i]=fac[i-1]*i%Mod;
	ifac[n*2]=pw(fac[n*2],Mod-2);
	per(i,n*2-1,0)ifac[i]=ifac[i+1]*(i+1)%Mod;
	cat[0]=1;
	rep(i,1,n)cat[i]=fac[i*2]*ifac[i]%Mod*ifac[i]%Mod*pw(i+1,Mod-2)%Mod;
	vector<ll>f=work(1,m);
	ll ans=0;
	rep(i,0,min((ll)f.size()-1,n))ans=(ans+cat[n/2-i/2]*f[i])%Mod;
	write(ans);
	return 0;
}