#include <bits/stdc++.h>

#include <atcoder/convolution>
#include <atcoder/modint>

using namespace std;
using namespace atcoder;

using mint = modint998244353;

std::vector<mint> fact, inv;

void init(int n) {
    fact.resize(n + 1);
    inv.resize(n + 1);
    fact[0] = 1;
    for (int i = 1; i <= n; i++) {
        fact[i] = fact[i - 1] * i;
    }
    inv[n] = fact[n].inv();
    for (int i = n; i >= 1; i--) {
        inv[i - 1] = inv[i] * i;
    }
}

mint ncr(int n, int r) {
    if (r < 0 or n < r) return 0;
    return fact[n] * inv[r] * inv[n - r];
}

int main() {
    init(600);

    int n, m;
    cin >> n >> m;
    vector<int> a(n), b(n);
    for (auto &&x : a) {
        cin >> x;
    }
    for (auto &&x : b) {
        cin >> x;
    }

    int offset = 300;
    vector<vector<mint>> count(m, vector<mint>(2 * offset + 1, 1));
    for (int i = 0; i < n; i++) {
        for (int j = -offset; j <= offset; j++) {
            count.at(i % m).at(j + offset) *=
                ncr(a.at(i) + b.at(i), a.at(i) + j);
        }
    }

    vector<mint> ans(1, 1);
    for (int i = 0; i < m; i++) {
        ans = convolution(ans, count.at(i));
    }

    assert(ans.size() == static_cast<size_t>(2 * m * offset + 1));
    cout << ans.at(m * offset).val() << endl;

    return 0;
}