#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAXN = 205;
ll dp[MAXN + 1][MAXN + 1][MAXN + 1][2];
void chmin(ll& x, ll y) {
x = min(x, y);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
ll Lt;
cin >> N >> Lt;
vector<ll> x(N + 3);
for (int i = 1; i <= N; ++i) {
cin >> x[i];
}
x[0] = 0;
x[N + 1] = Lt;
vector<ll> t(N + 3, -1);
for (int i = 1; i <= N; ++i) {
cin >> t[i];
}
const ll INF = 1e18;
t[0] = -INF;
t[N + 1] = -INF;
for (int i = 0; i <= N + 2; ++i) {
for (int j = 0; j <= N + 2; ++j) {
for (int k = 0; k <= N + 2; ++k) {
for (int l = 0; l < 2; ++l) {
dp[i][j][k][l] = INF;
}
}
}
}
dp[0][N + 1][0][0] = dp[0][N + 1][0][1] = 0;
auto dist = [&](ll X, ll Y) -> ll {
// if (min(abs(X - Y), Lt - abs(X - Y)) == 0) {
// cout << X << " " << Y << "\n";
// }
// assert(min(abs(X - Y), Lt - abs(X - Y)) > 0);
return min(abs(X - Y), Lt - abs(X - Y));
};
for (int l = 0; l < N; ++l) {
for (int r = N + 1; r - 1 > l; --r) {
for (int k = 0; k <= N; ++k) {
ll tim = min(dp[l][r][k][0] + dist(x[l + 1], x[l]),
dp[l][r][k][1] + dist(x[l + 1], x[r]));
if (tim <= t[l + 1]) {
chmin(dp[l + 1][r][k + 1][0],
tim);
} else {
chmin(dp[l + 1][r][k][0],
tim);
}
tim = min(dp[l][r][k][0] + dist(x[l], x[r - 1]),
dp[l][r][k][1] + dist(x[r], x[r - 1]));
if (tim <= t[r - 1]) {
chmin(dp[l][r - 1][k + 1][1],
tim);
} else {
chmin(dp[l][r - 1][k][1],
tim);
}
}
}
}
int res = 0;
for (int i = 0; i <= N + 1; ++i) {
for (int j = 0; j <= N + 1; ++j) {
for (int k = 0; k <= N; ++k) {
for (int z = 0; z < 2; ++z) {
if (dp[i][j][k][z] >= INF) continue;
res = max(res, k);
}
}
}
}
cout << res << "\n";
}
