#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include <debug.h>
#else
#define debug(...)
#endif
#define ft front
#define bk back
#define st first
#define nd second
#define ins insert
#define ers erase
#define pb push_back
#define pf push_front
#define _pb pop_back
#define _pf pop_front
#define lb lower_bound
#define ub upper_bound
#define mtp make_tuple
#define bg begin
#define ed end
#define all(x) (x).bg(), (x).ed()
#define sz(x) (int)(x).size()
typedef long long ll; typedef unsigned long long ull;
typedef double db; typedef long double ldb;
typedef pair<int, int> pi; typedef pair<ll, ll> pll;
typedef vector<int> vi; typedef vector<ll> vll; typedef vector<pi> vpi; typedef vector<pll> vpll;
typedef string str;
template<typename T> T gcd(T a, T b) { return (b == 0? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
#define FOR(i, l, r) for (int (i) = (l); (i) <= (r); ++(i))
#define FOS(i, r, l) for (int (i) = (r); (i) >= (l); --(i))
#define FRN(i, n) for (int (i) = 0; (i) < (n); ++(i))
#define FSN(i, n) for (int (i) = (n) - 1; (i) >= 0; --(i))
#define EACH(i, x) for (auto &(i) : (x))
#define WHILE while
#define file "TEST"
mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
ll rand(ll l, ll r) { return uniform_int_distribution<ll>(l, r)(rd); }
/*
----------------------------------------------------------------
END OF TEMPLATE
----------------------------------------------------------------
Tran The Bao - ghostwriter
Training for VOI23 gold medal
----------------------------------------------------------------
DIT ME CHUYEN BAO LOC
----------------------------------------------------------------
*/
const int oo = 1e9 + 5;
const int N = 202;
int n, l, x[N], t[N], rs = 0;
pi d[N][N][2][N];
#define dis(x, y) min((x - y + l) % l, (y - x + l) % l)
void minimize(pi &a, pi b) {
a.nd = min(a.nd, oo);
b.nd = min(b.nd, oo);
if (!a.st && !b.st) {
if (b.nd < a.nd) a = b;
return;
}
if (a.st && !b.st) return;
if (!a.st && b.st) {
a = b;
return;
}
if (a.nd > b.nd) a = b;
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
// freopen(file".inp", "r", stdin);
// freopen(file".out", "w", stdout);
cin >> n >> l;
FOR(i, 1, n) cin >> x[i];
FOR(i, 1, n) cin >> t[i];
FOR(i, 0, n + 1)
FOR(j, 0, n + 1)
FOR(stat, 0, 1)
FOR(z, 0, n)
d[i][j][stat][z] = {0, oo};
FOR(i, 0, n + 1)
FOS(j, n + 1, i + 1)
FOR(stat, 0, 1)
FOR(z, 0, n) {
pi &rs = d[i][j][stat][z];
if (i == 0 && j == n + 1) {
minimize(rs, !z? pi(1, 0) : pi(0, oo));
continue;
}
if (!stat) {
if (i) {
pi tmp = d[i - 1][j][0][z];
minimize(rs, {tmp.st, tmp.nd + dis(x[i], x[i - 1])});
tmp = d[i - 1][j][1][z];
minimize(rs, {tmp.st, tmp.nd + dis(x[i], x[j])});
if (z) {
pi tmp = d[i - 1][j][0][z - 1];
if (tmp.st && tmp.nd + dis(x[i], x[i - 1]) <= t[i]) {
tmp.nd += dis(x[i], x[i - 1]);
minimize(rs, tmp);
}
tmp = d[i - 1][j][1][z - 1];
if (tmp.st && tmp.nd + dis(x[i], x[j]) <= t[i]) {
tmp.nd += dis(x[i], x[j]);
minimize(rs, tmp);
}
}
}
}
else {
if (j <= n) {
pi tmp = d[i][j + 1][1][z];
minimize(rs, {tmp.st, tmp.nd + dis(x[j], x[j + 1])});
tmp = d[i][j + 1][0][z];
minimize(rs, {tmp.st, tmp.nd + dis(x[j], x[i])});
if (z) {
pi tmp = d[i][j + 1][1][z - 1];
if (tmp.st && tmp.nd + dis(x[j], x[j + 1]) <= t[j]) {
tmp.nd += dis(x[j], x[j + 1]);
minimize(rs, tmp);
}
tmp = d[i][j + 1][0][z - 1];
if (tmp.st && tmp.nd + dis(x[j], x[i]) <= t[j]) {
tmp.nd += dis(x[j], x[i]);
minimize(rs, tmp);
}
}
}
}
}
FOR(i, 0, n)
FOS(j, n + 1, i + 1)
FOR(stat, 0, 1)
FOR(z, 0, n)
if (d[i][j][stat][z].st)
rs = max(rs, z);
cout << rs;
return 0;
}
/*
----------------------------------------------------------------
From Benq:
stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
----------------------------------------------------------------
*/
