#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll cycle_len;
vector<pair<int, int>> a;
vector<vector<vector<array<ll, 2>>>> dp;
// Counter-clockwise
ll get_dist(ll l, ll r){
if (l < -1 || l > a.size()) return 1e15;
if (r < -1 || r > a.size()) return 1e15;
if (l == -1 || l == a.size()) l = 0;
else l = a[l].first;
if (r == -1 || r == a.size()) r = 0;
else r = a[r].first;
return (l + cycle_len - r) % cycle_len;
}
ll get_time(int idx){
if (idx == -1 || idx == a.size()) return -1;
return a[idx].second;
}
ll f(int l, int r, int picked, bool lr){
if (l == -1 || l == a.size()+1 || r == -1 || r == a.size()+1 || picked == -1) return 1e15;
if (l + r > a.size()) return 1e15;
if (l == 0 && r == 0){
if (picked) return 1e15;
return 0;
}
ll& value = dp[l][r][picked][lr];
if (value != -1) return value;
value = 1e15;
if (!lr){
// At left
// Case 1: From left
{
ll picking = f(l-1, r, picked-1, false) + get_dist(l-1, l-2);
if (picking <= get_time(l-1)) value = min(value, picking);
ll not_picking = f(l-1, r, picked, false) + get_dist(l-1, l-2);
value = min(value, not_picking);
}
// Case 2: From right
{
ll picking = f(l-1, r, picked-1, true) + get_dist(l-1, a.size()-r);
if (picking <= get_time(l-1)) value = min(value, picking);
ll not_picking = f(l-1, r, picked, true) + get_dist(l-1, a.size()-r);
value = min(value, not_picking);
}
}
else{
// At right
// Case 1: From right
{
ll picking = f(l, r-1, picked-1, true) + get_dist(a.size()-r+1, a.size()-r);
if (picking <= get_time(a.size()-r)) value = min(value, picking);
ll not_picking = f(l, r-1, picked, true) + get_dist(a.size()-r+1, a.size()-r);
value = min(value, not_picking);
}
// Case 2: From left
{
ll picking = f(l, r-1, picked-1, false) + get_dist(l-1, a.size()-r);
if (picking <= get_time(a.size()-r)) value = min(value, picking);
ll not_picking = f(l, r-1, picked, false) + get_dist(l-1, a.size()-r);
value = min(value, not_picking);
}
}
return value;
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
int n; cin >> n >> cycle_len;
a.resize(n);
for (int i=0; i<n; i++){
cin >> a[i].first;
a[i].first %= cycle_len;
}
for (int i=0; i<n; i++){
cin >> a[i].second;
}
sort(a.begin(), a.end());
dp.assign(n+1, vector<vector<array<ll, 2>>> (n+1, vector<array<ll, 2>> (n+1, array<ll, 2>({-1, -1}))));
for (int result = n; result >= 0; result--){
for (int l=0; l<=a.size(); l++){
for (int r=0; r<=a.size(); r++){
if (f(l, r, result, false) < 1e15 || f(l, r, result, true) < 1e15){
cout << result << "\n";
return 0;
}
}
}
}
}
