#include <atcoder/all>
using namespace std;
using namespace atcoder;
using mint = atcoder::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 + 1, 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 < N; i++){
        int rem = i % M;
        for(int j = -B[i]; j <= A[i]; j++) tb[rem][j + 300] *= comb[A[i] + B[i]][B[i] + j];
        for(int j = A[i] + 1; j <= 300; j++) tb[rem][j + 300] = 0;
        for(int j = B[i] + 1; j <= 300; j++) tb[rem][-j + 300] = 0;
    }

    vector<mint> dp(1, 1);
    for(int i = 0, s = 300 * M + 1; i < M; i++){
        dp = convolution(dp, tb[i]);
        if(dp.size() > s) dp.resize(s);
    }
    cout << dp.back().val() << '\n';
}