#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 1;
void chmin(int& a, int b) {
a = min(a, b);
}
void solve() {
int N, P;
cin >> N >> P;
vector<int> X(N), T(N);
for (int &v : X) {
cin >> v;
}
for (int &v : T) {
cin >> v;
}
X.insert(X.begin(), 0);
T.insert(T.begin(), 0);
N++;
vector dp(N, vector(N, vector(N, vector(2, INF))));
dp[0][0][0][0] = 0;
for (int len = 0; len < N - 1; len++) {
for (int L = 0; L < N; L++) {
int R = (L + len) % N;
for (int ans = 0; ans < N; ans++) {
for (int w = 0; w < 2; w++) {
int time = dp[L][R][ans][w];
if (w == 0) {
{
int delta = (X[L] - X[(L + N - 1) % N] + P) % P;
int add = time + delta <= T[(L + N - 1) % N];
chmin(dp[(L + N - 1) % N][R][ans + add][0], time + delta);
}
{
int delta = (X[(R + 1) % N] - X[L] + P) % P;
int add = time + delta <= T[(R + 1) % N];
chmin(dp[L][(R + 1) % N][ans + add][1], time + delta);
}
} else {
{
int delta = (X[R] - X[(L + N - 1) % N] + P) % P;
int add = time + delta <= T[(L + N - 1) % N];
chmin(dp[(L + N - 1) % N][R][ans + add][0], time + delta);
}
{
int delta = (X[(R + 1) % N] - X[R] + P) % P;
int add = time + delta <= T[(R + 1) % N];
chmin(dp[L][(R + 1) % N][ans + add][1], time + delta);
}
}
}
}
}
}
int res = 0;
for (int L = 0; L < N; L++) {
for (int R = 0; R < N; R++) {
for (int ans = 0; ans < N; ans++) {
for (int w = 0; w < 2; w++) {
if (dp[L][R][ans][w] != INF) {
res = max(res, ans);
}
}
}
}
}
cout << res << "\n";
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
}
