/*/ Author: kal013 /*/
// #pragma GCC optimize ("O3")
#include "bits/stdc++.h"
#include "ext/pb_ds/assoc_container.hpp"
#include "ext/pb_ds/tree_policy.hpp"
using namespace std;
using namespace __gnu_pbds;
template<class T>
using ordered_set = tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update> ;
template<class key, class value, class cmp = std::less<key>>
using ordered_map = tree<key, value, cmp, rb_tree_tag, tree_order_statistics_node_update>;
// find_by_order(k) returns iterator to kth element starting from 0;
// order_of_key(k) returns count of elements strictly smaller than k;
struct custom_hash { // Credits: https://codeforces.com/blog/entry/62393
static uint64_t splitmix64(uint64_t x) {
// http://xorshift.di.unimi.it/splitmix64.c
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
template<class T> ostream& operator<<(ostream &os, vector<T> V) {
os << "[ ";
for(auto v : V) os << v << " ";
return os << "]";
}
template<class T> ostream& operator<<(ostream &os, set<T> S){
os << "{ ";
for(auto s:S) os<<s<<" ";
return os<<"}";
}
template<class T> ostream& operator<<(ostream &os, unordered_set<T> S){
os << "{ ";
for(auto s:S) os<<s<<" ";
return os<<"}";
}
template<class T> ostream& operator<<(ostream &os, ordered_set<T> S){
os << "{ ";
for(auto s:S) os<<s<<" ";
return os<<"}";
}
template<class L, class R> ostream& operator<<(ostream &os, pair<L,R> P) {
return os << "(" << P.first << "," << P.second << ")";
}
template<class L, class R> ostream& operator<<(ostream &os, map<L,R> M) {
os << "{ ";
for(auto m:M) os<<"("<<m.first<<":"<<m.second<<") ";
return os<<"}";
}
template<class L, class R> ostream& operator<<(ostream &os, unordered_map<L,R> M) {
os << "{ ";
for(auto m:M) os<<"("<<m.first<<":"<<m.second<<") ";
return os<<"}";
}
template<class L, class R, class chash = std::hash<R> > ostream& operator<<(ostream &os, gp_hash_table<L,R,chash> M) {
os << "{ ";
for(auto m:M) os<<"("<<m.first<<":"<<m.second<<") ";
return os<<"}";
}
#define TRACE
#ifdef TRACE
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
cerr << name << " : " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
const char* comma = strchr(names + 1, ',');
cerr.write(names, comma - names) << " : " << arg1<<" | ";
__f(comma+1, args...);
}
#else
#define trace(...) 1
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
inline int64_t random_long(long long l,long long r){
uniform_int_distribution<int64_t> generator(l,r);
return generator(rng);
}
inline int64_t random_long(){
uniform_int_distribution<int64_t> generator(LLONG_MIN,LLONG_MAX);
return generator(rng);
}
/*/---------------------------Defines----------------------/*/
typedef vector<int> vi;
typedef pair<int,int> pii;
#define ll long long
#define F first
#define S second
#define pb push_back
#define endl "\n"
#define all(v) (v).begin(),(v).end()
/*/-----------------------Modular Arithmetic---------------/*/
const int mod=1e9+7;
inline int add(int x,int y){
x+=y;
if (x>=mod) return x-mod;
return x;
}
inline int sub(int x,int y){
x-=y;
if (x<0) return x+mod;
return x;
}
inline int mul(int x,int y){
return (x*1ll*y)%mod;
}
inline int power(int x,int y){
int ans=1;
while(y){
if (y&1) ans=mul(ans,x);
x=mul(x,x);
y>>=1;
}
return ans;
}
inline int inv(int x){
return power(x,mod-2);
}
/*/-----------------------------Code begins----------------------------------/*/
const int N = 405;
const int M = 205;
long long dp[N][N][2][M];
const ll INF = 1e15+10;
void solve(){
int n;
ll l;
cin>>n>>l;
vector<ll> X(2*n + 1),T(2*n + 1);
for(int i = 0; i < n; ++i){
cin>>X[i];
}
X[n] = l;
for(int i = 0; i<n; ++i){
X[n+i+1] = l + X[i];
}
for(int i = 0; i < n; ++i){
cin>>T[i];
}
T[n] = -1;
for(int i = 0; i<n; ++i){
T[n+i+1] = T[i];
}
int ans = 0;
for(int i = 0 ; i < N; ++i){
for(int j = 0; j < N ; ++j){
for(int k = 0 ; k < 2; ++k){
for(int l = 0; l < M; ++l){
dp[i][j][k][l] = INF;
}
}
}
}
dp[n][n][0][0] = 0;
dp[n][n][1][0] = 0;
for(int len = 1; len <= n; ++len){
for(int l_id = n; l_id + len >= n; --l_id){
int r_id = l_id + len;
for(int pos = 0; pos < 2; ++pos){
for(int k = 0; k <= len ; ++k){
long long& cur_dp = dp[l_id][r_id][pos][k];
cur_dp = INF;
if (pos == 0){
ll x_dif = X[l_id+1] - X[l_id];
cur_dp = min(dp[l_id + 1][r_id][pos][k] + x_dif, cur_dp);
cur_dp = min(dp[l_id+1][r_id][pos^1][k] + X[r_id] - X[l_id],cur_dp);
if (k >= 1 && dp[l_id+1][r_id][pos][k-1] + x_dif <= T[l_id]){
cur_dp = min(cur_dp,dp[l_id+1][r_id][pos][k-1] + x_dif);
}
if (k >= 1 && dp[l_id+1][r_id][pos^1][k-1] + X[r_id] - X[l_id] <= T[l_id]){
cur_dp = min(cur_dp, dp[l_id+1][r_id][pos^1][k-1] + X[r_id] - X[l_id]);
}
}
else{
ll x_dif = X[r_id] - X[r_id-1];
cur_dp = min(dp[l_id][r_id-1][pos][k] + x_dif, cur_dp);
cur_dp = min(dp[l_id][r_id-1][pos^1][k] + X[r_id] - X[l_id], cur_dp);
if (k >= 1 && dp[l_id][r_id-1][pos][k-1] + x_dif <= T[r_id]){
cur_dp = min(cur_dp,dp[l_id][r_id-1][pos][k-1] + x_dif);
}
if (k >= 1 && dp[l_id][r_id-1][pos^1][k-1] + X[r_id] - X[l_id] <= T[r_id]){
cur_dp = min(cur_dp, dp[l_id][r_id-1][pos^1][k-1] + X[r_id] - X[l_id]);
}
}
if (dp[l_id][r_id][pos][k] < INF){
ans = max(ans,k);
}
}
}
}
}
cout<<ans<<endl;
}
int main(){
// Use "set_name".max_load_factor(0.25);"set_name".reserve(512); with unordered set
// Or use gp_hash_table<X,null_type>
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
cout<<fixed<<setprecision(25);
cerr<<fixed<<setprecision(10);
auto start = std::chrono::high_resolution_clock::now();
int t=1;
// cin>>t;
while(t--) {
solve();
}
auto stop = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::nanoseconds>(stop - start);
// cerr << "Time taken : " << ((long double)duration.count())/((long double) 1e9) <<"s "<< endl;
}
