#include<bits/stdc++.h>
#include<atcoder/convolution>
using namespace std;
using namespace atcoder;
using ll = long long;
#define endl '\n'
const ll MOD = 998244353;
const int inf = 1 << 30;
const int N = 700;
ll fact[N];
ll invfact[N];

ll modpow(ll a, ll b, ll MOD){
	ll ret = 1;
	while(b > 0){
		if(b & 1){
			ret *= a;
			ret %= MOD;
		}
		a *= a;
		a %= MOD;
		b >>= 1;
	}
	return ret;
}

void init(){
	fact[0] = 1;
	for(int i = 1; i < N; i++) fact[i] = fact[i - 1] * i % MOD;
	invfact[N - 1] = modpow(fact[N - 1], MOD - 2, MOD);
	for(int i = N - 2; i >= 0; i--) invfact[i] = invfact[i + 1] * (i + 1) % MOD;
}

ll nCk(int n, int k){
	if(k < 0 || k > n) return 0;
	return (fact[n] * invfact[k] % MOD) * invfact[n - k] % MOD;
}

void solve(){
	int n, m;
	cin >> n >> m;
	vector<int> A(n), B(n);
	for(int i = 0; i < n; i++) cin >> A[i];
	for(int i = 0; i < n; i++) cin >> B[i];
	vector<int> miA(m, inf), miB(m, inf);
	
	for(int i = 0; i < n; i++){
		int p = i % m;
		miA[p] = min(miA[p], A[i]);
		miB[p] = min(miB[p], B[i]);
	}
	vector<vector<int>> poly(m, vector<int>());
	int zero = 0;
	for(int i = 0; i < m; i++){
		int d = miA[i] + miB[i] + 1;
		poly[i].resize(d);
		zero += miB[i];
		for(int k = -miB[i]; k <= miA[i]; k++){
			ll p = 1;
			for(int j = i; j < n; j += m){
				p *= nCk(A[j] + B[j], B[j] + k);
				p %= MOD;
			}
			poly[i][k + miB[i]] = p;
		}
	}
	queue<int> que;
	for(int i = 0; i < m; i++) que.push(i);
	while(que.size() >= 2){
		int i = que.front(); que.pop();
		int j = que.front(); que.pop();
		poly[i] = convolution(poly[i], poly[j]);
		que.push(i);
	}
	int i = que.front();
	ll ans = poly[i][zero];
	cout << ans << endl;

}

int main(){
	init();
	solve();
}