# include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
using namespace std;
const int N=205;
long long n,x[N],dp[N][N][N][2],t[N],le,ri,l,ans,ff,ff1;
long long go(long long x, long long xx) {
if (x<xx) swap(x,xx);
return min(x-xx,xx-x+l);
}
long long mn(long long a, long long b , long long c) {
return(min(a,min(b,c)));
}
int main() {
cin>>n>>l;
for (int i=1; i<=n; i++) {
cin>>x[i];
}
for (int i=1; i<=n; i++) {
cin>>t[i];
}
for (int le=0; le<=n+1; le++) {
for (int ri=0; ri<=n+1; ri++) {
for (int cnt=0; cnt<=n+1; cnt++) {
dp[le][ri][cnt][0]=dp[le][ri][cnt][1]=1e9;
}
}
}
dp[0][0][0][0]=0;
dp[0][0][0][1]=0;
x[0]=l;
for (int sz=1; sz<=n; sz++) {
for (int ri=0; ri<=sz; ri++) {
if (ri==sz) le=0;
else le=n-(sz-ri)+1;
ff=ff1=0;
for (int cnt=0; cnt<=sz; cnt++) {
dp[le][ri][cnt][0]=mn(dp[le][ri][cnt][0],dp[(le+1)%(n+1)][ri][cnt][0]+go(x[(le+1)%(n+1)],x[le]),dp[(le+1)%(n+1)][ri][cnt][1]+go(x[ri], x[le]));
if (ri)
dp[le][ri][cnt][1]=mn(dp[le][ri][cnt][1],dp[le][ri-1][cnt][1]+go(x[ri-1], x[ri]),dp[le][ri-1][cnt][0]+go(x[le],x[ri]));
/* if (cnt<sz) {
if (dp[le][ri][cnt][0]<=t[le]) {
dp[le][ri][cnt+1][0]=min(dp[le][ri][cnt+1][0],dp[le][ri][cnt][0]);
}
if (dp[le][ri][cnt][1]<=t[ri] && !ff1) {
dp[le][ri][cnt+1][1]=min(dp[le][ri][cnt+1][1],dp[le][ri][cnt][1]);
}
}*/
// if (cnt==5 && dp[le][ri][cnt][1]<1e9)cout<<le<<" "<<ri<<" "<<cnt<<" "<<dp[le][ri][cnt][1]<<endl;
if (dp[le][ri][cnt][0]<(long long)1e9 || dp[le][ri][cnt][1]<(long long)1e9) { ans=max(ans,(long long)cnt);}
}
// if (sz==2 && le==6 && ri==1) cout<<dp[6][1][2][1]<<endl;
for (int cnt=sz; cnt>=1; cnt--) {
if (dp[le][ri][cnt-1][1]<=t[ri] && !ff) {
ff=1;
dp[le][ri][cnt][1]=min(dp[le][ri][cnt][1],dp[le][ri][cnt-1][1]);
//if (sz==2 && le==6 && ri==1 && cnt==2)
// cout<<dp[le][ri][cnt][1]<<endl;
}
if (dp[le][ri][cnt-1][0]<=t[le] && !ff1) {
ff1=1;
dp[le][ri][cnt][0]=min(dp[le][ri][cnt][0],dp[le][ri][cnt-1][0]);
}
if (dp[le][ri][cnt][0]<(long long)1e9 || dp[le][ri][cnt][1]<(long long)1e9) { ans=max(ans,(long long)cnt);}
}
}
}
//cout<<dp[6][1][2][0]<<endl;
cout<<ans<<endl;
}
