#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#ifdef DEBUG
#include <time.h>
#endif
#define all(a) (a).begin(), (a).end()
#define rev(a) (a).rbegin(), (a).rend()
#define F first
#define S second
int recur_depth = 0;
#ifdef DEBUG
#define dbg(x) \
{ \
++recur_depth; \
auto x_ = x; \
--recur_depth; \
cerr << string(recur_depth, '\t') << "\e[91m" << __func__ << ":" \
<< __LINE__ << "\t" << #x << " = " << x_ << "\e[39m" << endl; \
}
#else
#define dbg(x)
#endif
using namespace std;
using namespace __gnu_pbds;
typedef pair<int, int> ii;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> llll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pair<int, int>> vii;
typedef vector<vii> vvii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pair<ll, ll>> vll;
typedef vector<vll> vvll;
typedef vector<bool> vb;
template <class type1>
using ordered_set = tree<type1, null_type, less<type1>, rb_tree_tag,
tree_order_statistics_node_update>;
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) {
return os << '(' << p.first << ", " << p.second << ')';
}
template <typename T_container, typename T = typename enable_if<
!is_same<T_container, string>::value,
typename T_container::value_type>::type>
ostream &operator<<(ostream &os, const T_container &v) {
os << '{';
string sep;
for (const T &x : v)
os << sep << x, sep = ", ";
return os << '}';
}
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-9;
// Saw solution
void solve() {
ll n, l;
cin >> n >> l;
vll left(n);
for (auto &i : left)
cin >> i.first;
for (auto &i : left)
cin >> i.second;
vll right = left;
left.push_back({0, 0});
sort(all(left));
right.push_back({l, 0});
sort(rev(right));
ll dp[n + 10][n + 10][n + 10][2];
auto dist = [&](int a, int b) {
return min(((a - b) % l + l) % l, ((b - a) % l + l) % l);
};
int ans = 0;
for (int lb = 0; lb <= n; lb++)
for (int rb = 0; lb + rb <= n; rb++)
for (int cnt = 0; cnt <= n; cnt++)
dp[lb][rb][cnt][0] = dp[lb][rb][cnt][1] = INF;
for (int lb = 1; lb <= n; lb++) {
if (dist(0, left[lb].first) <= left[lb].second) {
dp[lb][0][1][0] = dist(0, left[lb].first);
dp[lb][0][1][1] = dp[lb][0][1][0] * 2;
ans = 1;
}
}
for (int rb = 1; rb <= n; rb++) {
if (dist(0, right[rb].first) <= right[rb].second) {
dp[0][rb][1][1] = dist(0, right[rb].first);
dp[0][rb][1][0] = dp[0][rb][1][1] * 2;
ans = 1;
}
}
for (int cnt = 1; cnt <= n; cnt++) {
for (int lb = 0; lb <= n; lb++) {
for (int rb = 0; lb + rb <= n; rb++) {
if (lb > 0)
dp[lb][rb][cnt][0] = min(dp[lb][rb][cnt][0],
dp[lb - 1][rb][cnt][1] +
dist(right[rb].first, left[lb].first));
if (lb > 0)
dp[lb][rb][cnt][0] = min(
dp[lb][rb][cnt][0], dp[lb - 1][rb][cnt][0] +
dist(left[lb - 1].first, left[lb].first));
if (lb > 0 && dp[lb - 1][rb][cnt - 1][0] +
dist(left[lb - 1].first, left[lb].first) <=
left[lb].second)
dp[lb][rb][cnt][0] = min(
dp[lb][rb][cnt][0], dp[lb - 1][rb][cnt - 1][0] +
dist(left[lb - 1].first, left[lb].first));
if (lb > 0 && dp[lb - 1][rb][cnt - 1][1] +
dist(right[rb].first, left[lb].first) <=
left[lb].second)
dp[lb][rb][cnt][0] = min(dp[lb][rb][cnt][0],
dp[lb - 1][rb][cnt - 1][1] +
dist(right[rb].first, left[lb].first));
if (rb > 0)
dp[lb][rb][cnt][1] = min(dp[lb][rb][cnt][1],
dp[lb][rb - 1][cnt][0] +
dist(left[lb].first, right[rb].first));
if (rb > 0)
dp[lb][rb][cnt][1] =
min(dp[lb][rb][cnt][1],
dp[lb][rb - 1][cnt][1] +
dist(right[rb - 1].first, right[rb].first));
if (rb > 0 && dp[lb][rb - 1][cnt - 1][1] +
dist(right[rb - 1].first, right[rb].first) <=
right[rb].second)
dp[lb][rb][cnt][1] =
min(dp[lb][rb][cnt][1],
dp[lb][rb - 1][cnt - 1][1] +
dist(right[rb - 1].first, right[rb].first));
if (rb > 0 && dp[lb][rb - 1][cnt - 1][0] +
dist(left[lb].first, right[rb].first) <=
right[rb].second)
dp[lb][rb][cnt][1] = min(dp[lb][rb][cnt][1],
dp[lb][rb - 1][cnt - 1][0] +
dist(left[lb].first, right[rb].first));
if (dp[lb][rb][cnt][0] < INF || dp[lb][rb][cnt][1] < INF)
ans = max(ans, cnt);
}
}
}
cout << ans << "\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
clock_t start = clock();
int test_cases = 1;
// cin >> test_cases;
while (test_cases--)
solve();
#ifdef DEBUG
cerr << fixed << setprecision(10)
<< "\nTime Taken: " << (double)(clock() - start) / CLOCKS_PER_SEC
<< "s\n";
#endif
return 0;
}
