#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int N,M;
int A[202020],B[202020];
ll dp[2][303][303];
const ll mo=998244353;

ll dp2[606];
ll dp3[303][303*303*2];

ll comb(ll N_, ll C_) {
	const int NUM_=400001;
	static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1];
	if (fact[0]==0) {
		inv[1]=fact[0]=factr[0]=1;
		for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo;
		for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo;
	}
	if(C_<0 || C_>N_) return 0;
	return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo;
}

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>M;
	FOR(i,N) cin>>A[i];
	FOR(i,N) cin>>B[i];
	FOR(i,M) {
		FOR(j,301) dp[0][i][j]=dp[1][i][j]=1;
	}
	FOR(j,301) FOR(i,N) {
		(dp[0][i%M][j]*=comb(A[i],j))%=mo;
		(dp[1][i%M][j]*=comb(B[i],j))%=mo;
	}
	dp3[0][0]=1;
	FOR(i,M) {
		ZERO(dp2);
		FOR(x,301) FOR(y,301) (dp2[300+x-y]+=dp[0][i][x]*dp[1][i][y])%=mo;
		FOR(j,600*i+1) {
			FOR(x,601) (dp3[i+1][j+x]+=dp2[x]*dp3[i][j])%=mo;
		}
	}
	cout<<dp3[M][300*M]<<endl;
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}