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

int main(){
    int N, M, r = 600, v;
    cin >> N >> M;
    vector<int> A(N);
    for(auto &&v:A)cin >> v;
    vector<vector<mint>> comb(r + 1, vector<mint>(r + 1)), tb(M + 1, vector<mint>(r + 1, 1));
    for(int i = 1; i <= r; i++){
        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++){
        cin >> v;
        int rem = i % M;
        for(int j = 0; j <= 600; j++){
            tb[rem][j] *= (-v + 300 <= j && j <= A[i] + 300 ? comb[v + A[i]][j + v - 300] : 0);
        }
    }
    vector<mint> dp(1, 1);
    for(int i = 0; i < M; i++) dp = convolution(dp, tb[i]);
    cout << dp[300 * M].val() << '\n';
}