#include<bits/stdc++.h>
#define mod 998244353
#define int long long
inline int read()
{	int x=0;
	bool f=0;
	char c=getchar();
	while(!isdigit(c))f|=(c=='-'),c=getchar();
	while(isdigit(c))x=x*10+(c&15),c=getchar();
	return f?-x:x;
}
using namespace std;
int n,m,a[1005],b[1005],prea[1<<13],preb[1<<13],dp[1005][1<<13],g[1005][1<<13],C[1005][1005],jc[1005],maxn;
inline int ksm(int x,int y=mod-2)
{	int res=1;
	while(y)
	{	if(y&1)res=res*x%mod;
		x=x*x%mod;
		y>>=1;
	}
	return res;
}
signed main()
{
	n=read(),m=read();
	for(int i=0;i<m;++i)a[i]=read();
	for(int i=0;i<m;++i)b[i]=read();
	for(int i=0;i<=n;++i)
	{	C[i][0]=1;
		for(int j=1;j<=i;++j)C[i][j]=(C[i-1][j]+C[i-1][j-1])%mod;
	}
	jc[0]=1;
	maxn=(1<<m)-1;
	for(int i=1;i<=n;++i)jc[i]=jc[i-1]*i%mod;
	for(int i=1;i<=maxn;++i)
	{	int x=__lg(i),j=i^(1<<x);
		prea[i]=prea[j]+a[x]-b[x],preb[i]=preb[j]+b[x];
	}
	int hf=0;
	for(int i=0;i<m;++i)if(!b[i])hf|=(1<<i);
	g[0][hf]=1;
	for(int i=1;i<=preb[maxn];++i)
		for(int S=0;S<=maxn;++S)
		{	if(n-(i-1)<=prea[S])continue;
    		int gl=ksm((n-(i-1))-prea[S]),v=(n-(i-1))*gl%mod;
	    	(g[i][S]+=g[i-1][S]*gl)%=mod;
    		(dp[i][S]+=gl*((dp[i-1][S]+v*g[i-1][S]%mod)%mod)%mod)%=mod;
	    	if(i-1<preb[S])continue;
    		for(int x=0;x<=m-1;++x)
				if(!(S>>x&1))
				{	int T=S|(1<<x);
    				int c=C[a[x]][b[x]]*jc[b[x]]%mod*C[(i-1)-preb[S]][b[x]-1]%mod;
	    			(g[i][T]+=g[i-1][S]*gl%mod*c%mod)%=mod;
    				(dp[i][T]+=gl*c%mod*((dp[i-1][S]+v*g[i-1][S]%mod)%mod)%mod)%=mod;
    			}
    	}
  	cout<<dp[preb[maxn]][maxn];
  	return 0;
}