#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for (int i=0; i<n; i++)
#define pb push_back
typedef long long ll;

const int MAX = 310;
const ll MOD = 998244353;
ll fact[MAX], finv[MAX], inv[MAX];

void Cinit() {
    fact[0] = fact[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i=2; i<MAX; i++) {
        fact[i] = fact[i-1]*i%MOD;
        inv[i] = MOD-inv[MOD%i]*(MOD/i)%MOD;
        finv[i] = finv[i-1]*inv[i]%MOD;
    }
}

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

vector<ll> coef[310];

vector<ll> rec(int l, int r) {
    if (l==r) return coef[l];
    int m = (l+r)/2;
    vector<ll> res1 = rec(l, m);
    vector<ll> res2 = rec(m+1, r);
    vector<ll> res = convolution(res1, res2);
    return res;
}

int main() {
    cin.tie(0); ios::sync_with_stdio(false);
    
    int N, M; cin >> N >> M;
    int A[N], B[N];
    rep(i, N) cin >> A[i];
    rep(i, N) cin >> B[i];
    Cinit();
    
    int offset = 300;
    rep(i, M) {
        coef[i].resize(601);
        rep(j, 601) coef[i][j] = 1ll;
    }
    
    rep(i, M) {
        for (int j=i; j<N; j+=M) {
            vector<ll> a(601, 0), b(601, 0);
            rep(k, A[j]+1) a[k+offset] = C(A[j], k)%MOD;
            rep(k, B[j]+1) b[offset-k] = C(B[j], k)%MOD;
            vector<ll> conv = convolution(a, b);
            for (int k=0; k<601; k++) {
                coef[i][k] *= conv[k+offset];
                coef[i][k] %= MOD;
            }
        }
    }
    
    vector<ll> res = rec(0, M-1);
    cout << res[M*offset] << endl;
}