#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF (int)1e18
#define f first
#define s second
mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());
const int N = 201;
int n, l;
int x[N], t[N];
int dp[N][N][N][2];
int f(int x, int y){
int ans = abs(x - y);
ans = min(ans, abs(ans - l));
return ans;
}
void ckmin(int &a, int b){
a = min(a, b);
}
void Solve()
{
cin >> n >> l;
for (int i = 1; i <= n; i++) cin >> x[i];
for (int i = 1; i <= n; i++) cin >> t[i];
for (int i = 0; i < N; i++){
for (int j = 0; j < N; j++){
for (int k = 0; k < N; k++){
dp[i][j][k][0] = dp[i][j][k][1] = INF;
}
}
}
int t1 = f(0, x[1]);
dp[1][n + 1][t1 <= t[1]][0] = t1;
int t2 = f(0, x[n]);
dp[0][n][t2 <= t[n]][1] = t2;
for (int sum = 2; sum <= n; sum++){
for (int i = 0; i < sum; i++){
int j = sum - 1 - i;
j = n + 1 - j;
for (int tk = 0; tk < sum; tk++){
if (i != 0){
//last = 0
{
//go to i + 1
t1 = dp[i][j][tk][0] + f(x[i], x[i + 1]);
ckmin(dp[i + 1][j][tk + (t1 <= t[i + 1])][0], t1);
}
{
//go to j - 1
t1 = dp[i][j][tk][0] + f(x[i], x[j - 1]);
ckmin(dp[i][j - 1][tk + (t1 <= t[j - 1])][1], t1);
}
}
if (i + 1 != sum){
//last = 1
{
//go to i + 1
t1 = dp[i][j][tk][1] + f(x[j], x[i + 1]);
ckmin(dp[i + 1][j][tk + (t1 <= t[i + 1])][0], t1);
}
{
//go to j - 1
t1 = dp[i][j][tk][1] + f(x[j], x[j - 1]);
ckmin(dp[i][j - 1][tk + (t1 <= t[j - 1])][1], t1);
}
}
}
}
}
int ans = 0;
for (int i = 0; i < N; i++){
for (int j = 0; j < N; j++){
for (int k = 0; k < N; k++){
for (int l = 0; l < 2; l++){
if (dp[i][j][k][l] != INF){
ans = max(ans, k);
}
}
}
}
}
cout << ans << "\n";
}
int32_t main()
{
auto begin = std::chrono::high_resolution_clock::now();
ios_base::sync_with_stdio(0);
cin.tie(0);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++)
{
//cout << "Case #" << i << ": ";
Solve();
}
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
return 0;
}
