#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1100,M=4400,mod=998244353;

int ksm(int a,int x){
	int tot=1;
	while(x){
		if(x & 1ll) tot=tot*a%mod;
		a=a*a%mod;
		x>>=1ll;
	}
	return tot;
}

int mul[N],inv[N];
void init(int lim){
	mul[0]=inv[0]=1;
	for(int i=1;i<=lim;i++) mul[i]=mul[i-1]*i%mod;
	inv[lim]=ksm(mul[lim],mod-2);
	for(int i=lim-1;i>=1;i--) inv[i]=inv[i+1]*(i+1)%mod;
}
int C(int m,int n){
	if(m<0 || n<0 || m<n) return 0;
	return mul[m]*inv[n]%mod*inv[m-n]%mod;
}
void gmod(int &x){
	x%=mod;
}

int n,m,alc=1;
int a[N],b[N];
int f[M][N],g[M][N];
int sumc[M],sumb[M];

inline int A(int t,int mac){
	return ksm(n-t-sumc[mac],mod-2);
}
inline int B(int t,int mac){
	return (n-t)*A(t,mac)%mod;
}

signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	init(N-5);
	cin>>n>>m;
	for(int i=0;i<m;i++) cin>>a[i];
	for(int i=0;i<m;i++) cin>>b[i];
	for(int mac=0;mac<(1<<m);mac++){
		for(int i=0;i<m;i++){
			if(!(mac>>i & 1)){
				sumc[mac]+=a[i]-b[i];
				sumb[mac]+=b[i];
			}
		}
	}
	for(int i=0;i<m;i++) alc=alc*mul[a[i]]%mod*inv[a[i]-b[i]]%mod;
	
	f[0][0]=1;
	for(int mac=0;mac<(1<<m);mac++){
		// cout<<mac<<": "<<endl;
		for(int i=n;i>=0;i--){
			if(!f[mac][i] && !g[mac][i]) continue;
			// cout<<mac<<" "<<i<<": "<<endl;
			int t=sumb[mac]+i-1;
			if(i){
				gmod(f[mac][i-1]+=f[mac][i]*A(t,mac)%mod);
				gmod(g[mac][i-1]+=g[mac][i]*A(t,mac)%mod);
				gmod(g[mac][i-1]+=f[mac][i]*A(t,mac)%mod*B(t,mac)%mod);
				// cout<<"   => "<<mac<<" "<<i-1<<" ("<<t<<", "<<A(t,mac)<<", "<<A(t,mac)*B(t,mac)%mod<<")"<<endl;
			}
			
			for(int x=0;x<m;x++){
				if(mac>>x & 1) continue;
				int nmac=mac | (1<<x);
				gmod(f[nmac][i+b[x]-1]+=f[mac][i]*C(i+b[x]-1,i)%mod*A(t,nmac)%mod);
				gmod(g[nmac][i+b[x]-1]+=g[mac][i]*C(i+b[x]-1,i)%mod*A(t,nmac)%mod);
				gmod(g[nmac][i+b[x]-1]+=f[mac][i]*C(i+b[x]-1,i)%mod*A(t,nmac)%mod*B(t,nmac)%mod);
				
				// cout<<t<<" "<<mac<<" "<<n-t-sumc[nmac]<<endl;
				// cout<<"   => "<<nmac<<" "<<i-1+b[x]<<" ("<<t<<", "<<C(i+b[x]-1,i)<<", "<<A(t,nmac)<<", "<<A(t,nmac)*B(t,nmac)%mod<<")"<<endl;
			}
		}
		// for(int i=0;i<=n;i++) cout<<f[mac][i]<<" ";
		// cout<<endl;
		// for(int i=0;i<=n;i++) cout<<g[mac][i]<<" ";
		// cout<<endl;
	}
	cout<<g[(1<<m)-1][0]*alc%mod;
}