#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define AquA cin.tie(0);ios_base::sync_with_stdio(0);
#define fs first
#define sc second
#define p_q priority_queue
//#define int long long
using namespace std;
typedef long long ll;
const ll inf=2e16;
ll dp[205][205][205][2];
int main(){
AquA;
int n;
ll l;
cin >> n >> l;
vector<ll> v(n+3),rv(n+3),t(n+3),rt(n+3);
t[0]=rt[0]=4e9;
rv[0]=l;
v[0]=0;
for(int i=1;i<=n;i++){
cin >> v[i];
rv[n-i+1]=v[i];
}
for(int i=1;i<=n;i++){
cin >> t[i];
rt[n-i+1]=t[i];
}
for(int i=0;i<205;i++){
for(int j=0;j<205;j++){
for(int k=0;k<205;k++){
dp[i][j][k][0]=dp[i][j][k][1]=inf;
}
}
}
dp[0][0][0][0]=dp[0][0][0][1]=0;
int maxx=0;
for(int len=0;len<=n;len++){
for(int i=0;i<=len;i++){
int j=len-i;
for(int k=0;k<=len;k++){
ll z=dp[i][j][k][0];
if(z!=inf){
maxx=max(maxx,k);
}
if(z+v[i+1]-v[i]<=t[i+1]){
dp[i+1][j][k+1][0]=min(dp[i+1][j][k+1][0],z+v[i+1]-v[i]);
}
else{
dp[i+1][j][k][0]=min(dp[i+1][j][k][0],z+v[i+1]-v[i]);
}
if(z+v[i]-v[0]+rv[0]-rv[j+1]<=rt[j+1]){
dp[i][j+1][k+1][1]=min(dp[i][j+1][k+1][1],z+v[i]-v[0]+rv[0]-rv[j+1]);
}
else{
dp[i][j+1][k][1]=min(dp[i][j+1][k][1],z+v[i]-v[0]+rv[0]-rv[j+1]);
}
z=dp[i][j][k][1];
if(z!=inf){
maxx=max(maxx,k);
}
if(z+rv[j]-rv[j+1]<=rt[j+1]){
dp[i][j+1][k+1][1]=min(dp[i][j+1][k+1][1],z+rv[j]-rv[j+1]);
}
else{
dp[i][j+1][k][1]=min(dp[i][j+1][k][1],z+rv[j]-rv[j+1]);
}
if(z+rv[0]-rv[j]+v[i+1]-v[0]<=t[i+1]){
dp[i+1][j][k+1][0]=min(dp[i+1][j][k+1][0],z+rv[0]-rv[j]+v[i+1]-v[0]);
}
else{
dp[i+1][j][k][0]=min(dp[i+1][j][k][0],z+rv[0]-rv[j]+v[i+1]-v[0]);
}
}
}
}
cout << maxx << "\n";
return 0;
}
