#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define i128 __int128
#define mem(x) memset(x,0,sizeof(x))
#define endl "\n"
#define printYes cout << "Yes\n"
#define printYES cout << "YES\n"
#define printNo cout << "No\n"
#define printNO cout << "NO\n"
#define lowbit(x) ((x)&(-(x)))
#define pb push_back
#define mkp make_pair
#define pii pair<ll,ll>
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
#define rep(i,j,k) for (int i=(j);i<=(k);i++)
#define per(i,j,k) for (int i=(j);i>=(k);i--)
#define pcnt(x) __builtin_popcount(x)
mt19937 rnd(time(0));
template<class T>void chkmin(T&x,T y){x=min(x,y);}
template<class T>void chkmax(T&x,T y){x=max(x,y);}

const ll inf=1000000000000000000; 
//const ll inf=1000000000;
const ll mod=998244353;
//const ll mod=1000000007;

const int N=1e5+5;
int n,m; 
ll jc[N+10],inv[N+10];
ll ksm(ll x,ll y)
{
	ll res=1;
	while (y)
	{
		if (y&1) res=res*x%mod;
		x=x*x%mod,y>>=1;
	}
	return res;
}
inline ll C(ll x,ll y)
{
	if (y<0||y>x) return 0;
	return jc[x]*inv[y]%mod*inv[x-y]%mod;
}
void init()
{
	jc[0]=1;
	for (int i=1;i<=N;i++) jc[i]=jc[i-1]*i%mod;
	inv[N]=ksm(jc[N],mod-2);
	for (int i=N-1;i>=0;i--) inv[i]=inv[i+1]*(i+1)%mod;
}

int a[15],b[15];
pii dp[1005][1<<12];
pii dfs(int x,int s)
{
	if (s==(1<<m)-1)
	{
		if (x==0) return mkp(1,0);
		return mkp(0,0);
	}
	if (dp[x][s].fi!=-1) return dp[x][s];
	ll num=0,res=0,sa=0,sb=-x;
	rep(i,0,m-1)
	{
		if (s&(1<<i)) sa+=a[i]-b[i];
		else sb+=a[i];
	}
	if (sb<=0) return mkp(0,0);
	ll val=(sa+sb)*ksm(sb,mod-2)%mod;
	ll W=ksm(sb,mod-2);
	rep(i,0,m-1)
	{
		if (s&(1<<i)) continue;
		if (b[i]>x+1) continue;
		//ll val=0;
		//rep(j,1,b[i]) (val+=(sa+j)*ksm(j,mod-2))%=mod;
		ll w=W*C(x,b[i]-1)%mod*C(a[i],b[i])%mod*jc[b[i]]%mod;
		pii z=dfs(x+1-b[i],s|(1<<i));
		(num+=w*z.fi)%=mod;
		(res+=w*(z.se+z.fi*val%mod))%=mod;
	}
	pii z=dfs(x+1,s);
	(num+=z.fi*W)%=mod;
	(res+=(z.se+z.fi*val%mod)*W)%=mod;
	return dp[x][s]=mkp(num,res);
}


int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin >> n >> m;
	rep(i,0,m-1) cin >> a[i];
	rep(i,0,m-1) cin >> b[i];
	init();
	memset(dp,-1,sizeof(dp));
	int s=0;
	rep(i,0,m-1) if (b[i]==0) s|=(1<<i);
	pii res=dfs(0,s);
	cout << res.se*ksm(res.fi,mod-2)%mod;//res.fi
	return 0;
}