#include<bits/stdc++.h>
#define int long long
using namespace std;
int pos[205];
int t[205];
int dis[205][205];
int rr[205][205];
int ll[205][205];
int n,l;
int inf=1e18;
struct info{
int c,cnt,id,ll,rr;
info(int _c,int _cnt,int _id,int _ll,int _rr){
c=_c,cnt=_cnt,id=_id,ll=_ll,rr=_rr;
}
friend bool operator<(info a,info b){
if(a.c==b.c){
if(a.cnt==b.cnt){
if(a.ll==b.ll){
return a.rr>b.rr;
}return a.ll<b.ll;
}else return a.cnt>b.cnt;
}else return a.c>b.c;
}
};
int g(int a,int b){
return min(abs(a-b),l-abs(a-b));
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cin>>n>>l;
for(int i=1;i<=n;i++)cin>>pos[i];
for(int i=1;i<=n;i++)cin>>t[i];
for(int i=1;i<=n;i++)for(int j=1;j<=n;j++)dis[i][j]=inf;
priority_queue<info,vector<info>>pq;
for(int i=1;i<=n;i++){
int ll=n+1,rr=0;
int f=0;
int x=pos[i]-l;
if(x<0)x+=l,f=1;
if(x<=t[i])pq.push(info(x,1,i,f?ll:min(ll,i),f?max(rr,i):rr));
f=0,x=l-pos[i];
if(x<0)x+=l,f=1;
if(x<=t[i])pq.push(info(x,1,i,f?ll:min(ll,i),f?max(rr,i):rr));
}
int ans=0;
while(!pq.empty()){
auto temp=pq.top();
pq.pop();
int c=temp.c,cnt=temp.cnt,id=temp.id,ll=temp.ll,rr=temp.rr;
if(dis[id][cnt]<=c)continue;
//cerr<<id<<" "<<cnt<<" "<<c<<" "<<rr<<" "<<ll<<'\n';
dis[id][cnt]=c;
if(c<=inf)ans=max(ans,cnt);
for(int i=rr+1;i<ll;i++){
if(i==id)continue;
int f=0;
int x=pos[i]-pos[id];
if(x<0)x+=l,f=1;
if(x+c<=t[i])pq.push(info(x+c,cnt+1,i,f?ll:min(ll,i),f?max(rr,i):rr));
f=0,x=pos[id]-pos[i];
if(x<0)x+=l,f=1;
if(x+c<=t[i])pq.push(info(x+c,cnt+1,i,f?ll:min(ll,i),f?max(rr,i):rr));
}
}
cout<<ans;
}
