#include <bits/stdc++.h>
#define forn(i,n) for(int i=0;i<int(n);++i)
#define fort(i,n) for(int i=0;i<=int(n);++i)
#define fori(i,a,n) for(int i=a;i<int(n);++i)
#define forit(i,a,n) for(int i=a;i<=int(n);++i)
#define ALL(v) v.begin(),v.end()
#define SZ(v) (int)v.size()
#define DBG(a) cerr<<#a<<" = "<<(a)<<endl
#define DBGA(a) cerr<<#a<<" = "<<(a)<<", ";
#define DBG2(a,b) do{DBGA(a)DBG(b);}while(0)
#define DBG3(a,b,c) do{DBGA(a)DBGA(b)DBG(c);}while(0)
#define DBG4(a,b,c,d) do{DBGA(a)DBGA(b)DBGA(c)DBG(d);}while(0)
#define LINE cerr<<"===================================="<<endl
using namespace std;
template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v){
os<<"[";
forn(i,v.size()){
if(i) os<<" ";
os<<v[i];
}
os<<"]";
return os;
}
typedef long long ll;
typedef long double ld;
const int INF = 2000000000;
void assign(int &a, int v){
a = min(a, v);
}
void solve(){
int n, L;
cin>>n>>L;
vector<int> xs{0};
forn(i,n){
int x;
cin>>x;
xs.push_back(x);
}
xs.push_back(L);
vector<int> ts{0};
forn(i,n){
int t;
cin>>t;
ts.push_back(t);
}
ts.push_back(INF);
n+=2; // inicial y final
int dp[n][n][n];
forn(i,n) forn(j,n) forn(k,n) dp[i][j][k] = INF;
dp[0][0][n-1] = 0;
for(int i = 0; i < n; ++i){ // cantidad de estampas
for(int j = 1; j < n; ++j){ // tamaño de la ventana
for(int l = 0; l < n; ++l){ // donde estoy parado
// recorrido hacia la izquierda
int r = l - j;
if(r < 0){
r=r+n;
if(r-l > 1){ // todavía hay espacio
// aumentar el l
int t = xs[l+1] - xs[l];
int nt = dp[i][l][r] + t;
assign(dp[i + bool(nt <= ts[l+1])][l+1][r], nt);
// reducir el r
t = L - xs[r-1] + xs[l];
nt = dp[i][l][r] + t;
assign(dp[i + bool(nt <= ts[r-1])][r-1][l], nt);
}
}
// recorrido hacia la derecha
r = l + j;
if(r >= n){
r=r-n;
if(l-r > 1){
// reducir el l
int t = xs[l] - xs[l-1];
int nt = dp[i][l][r] + t;
assign(dp[i + bool(nt <= ts[l-1])][l-1][r], nt);
// aumentar el r
t = L - xs[l] + xs[r+1];
nt = dp[i][l][r] + t;
assign(dp[i + bool(nt <= ts[r+1])][r+1][l], nt);
}
}
}
}
}
int ans = 0;
forn(i,n) forn(j,n) forn(k,n) if(dp[i][j][k] < INF) ans = i;
cout<<ans<<"\n";
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef LOCAL
assert(freopen("input.in", "r", stdin));
//~ freopen("output.out", "w", stdout);
#endif
#ifdef LOCAL
int tcs; cin>>tcs;
while(tcs--)
#endif
solve();
return 0;
}
