#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod=998244353;
#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef __uint128_t L;
struct FastMod {
	ull b, m;
	FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
	ull reduce(ull a) {
		ull q = (ull)((L(m) * a) >> 64);
		ull r = a - q * b; // can be proven that 0 <= r < 2*b
		return r >= b ? r - b : r;
	}
};
FastMod F(mod);

int n,m;
const int iu=2000;
ll f[2005],inf[2005];
ll C[2005][2005];
ll pw(ll x,ll y){
	if(y==0) return 1;
	if(y%2) return F.reduce(x*pw(x,y-1));
	ll res=pw(x,y/2);
	return F.reduce(res*res);
}
int a[15],b[15];
ll ff[4096][1005];
int deg[4096];
ll dp[4096][1005];
int main(){
	ios::sync_with_stdio(false);cin.tie(0);
	cin >> n >> m;
	for(int i=0; i<m ;i++) cin >> a[i];
	int ST=0;
	for(int i=0; i<m ;i++){
		cin >> b[i];
		if(b[i]==0) ST|=1<<i;
	}
	C[0][0]=1;f[0]=inf[0]=1;
	for(int i=1; i<=iu ;i++){
		f[i]=f[i-1]*i%mod;
		inf[i]=pw(f[i],mod-2);
		C[i][0]=1;
		for(int j=1; j<=i ;j++) C[i][j]=F.reduce(C[i-1][j]+C[i-1][j-1]);
	}
	ff[0][0]=1;
	deg[0]=0;
	for(int i=1; i<(1<<m) ;i++){
		if(i&ST) continue;
		int w=i&-i;
		int g=0;
		while(w!=(1<<g)) ++g;
		for(int j=0; j<m ;j++){
			if(((i>>j)&1) && b[j]<b[g]) g=j;
		}
		w=1<<g;
		deg[i]=deg[i^w]+b[g]-1;
		for(int j=0; j<=deg[i^w] ;j++){
			for(int k=0; k<b[g] ;k++){
				ff[i][j+k]=F.reduce(ff[i][j+k]+ff[i^w][j]*C[a[g]][k]);
			}
		}
	}
	dp[ST][0]=1;
	ll ans=0;
	for(int i=0; i<(1<<m)-1 ;i++){
		for(int j=0; j<=n ;j++){
			if(dp[i][j]==0) continue;
			int can=0;
			int trash=0;
			int done=0;
			for(int k=0; k<m ;k++){
				if((i>>k)&1) trash+=a[k]-b[k],done+=b[k];
				else can+=a[k];
			}
			can-=j-done;
			ll cost=(trash*f[can-1]%mod*inf[can]%mod+1);
			ans=(ans+cost*dp[i][j])%mod;
			ll ways=1;
			int mask=((1<<m)-1)^i;
			for(int k=0; k<m ;k++){//calculate ways to complete set k
				if((i>>k)&1) continue;
				int g=k;
				if(j-done<b[g]-1) continue;
				ll num=F.reduce(ff[mask^(1<<k)][j-done-b[g]+1]*C[a[g]][b[g]-1]);
				ll den=ff[mask][j-done];
				ll prob=F.reduce((a[g]-b[g]+1)*f[can-1]%mod*inf[can]);
				
				prob=F.reduce(num*prob%mod*pw(den,mod-2));
				dp[i|(1<<k)][j+1]=F.reduce(dp[i|(1<<k)][j+1]+prob*dp[i][j]);
				ways=(ways+mod-prob)%mod;
			}
			dp[i][j+1]=(dp[i][j+1]+dp[i][j]*ways)%mod;
		}
	}
	cout << ans << '\n';
}