#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint998244353;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int N, M, r = 600;
    cin >> N >> M;
    vector<int> A(N), B(N);
    for(auto &&v:A)cin >> v;
    for(auto &&v:B)cin >> v;

    vector<vector<mint>> comb(r + 1), tb(M, vector<mint>(r + 1, 1));
    for(int i = 1; i <= r; i++){
        comb[i].resize(i + 1);
        comb[i][0] = comb[i][i] = 1;
        for(int j = 1; j < i; j++) comb[i][j] = comb[i - 1][j - 1] + comb[i - 1][j];
    }

    for(int i = 0; i < M; i++){
        for(int k = i; k < N; k += M){
            for(int j = -B[k]; j <= A[k]; j++) tb[i][j + 300] *= comb[A[k] + B[k]][B[k] + j];
            for(int j = A[k] + 1; j <= 300; j++) tb[i][j + 300] = 0;
            for(int j = B[k] + 1; j <= 300; j++) tb[i][-j + 300] = 0;
        }
    }

    int s = 300 * M + 1;
    auto merge = [&](int i, int j){
        if(j >= M)return;
        tb[i] = convolution(tb[i], tb[j]);
        if(tb[i].size() > s) tb[i].resize(s);
    };

    for(int i = 0; i < 9; i++){
        int d = 1 << i + 1;
        for(int j = 0; j < M; j += d) merge(j, j + (1 << i));
    }
    cout << tb[0][300 * M].val() << '\n';
}