#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, rem = 0; i < N; i++){
        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;
        if(++rem >= M)rem -= M;
    }

    cout << accumulate(tb.begin(), tb.end(), vector<mint>(1, 1), [](vector<mint> lhs, vector<mint> rhs){
        return convolution(lhs, rhs);
    })[300 * M].val() << '\n';
}