#include<bits/stdc++.h>
typedef long long ll;
#define pb push_back
#define fr first
#define sc second
#define endl '\n'
using namespace std;
#define mid ((left+right)>>1)
int n,k;
int loc[223],t[223];
int dp[202][202][202][2];
int main(){
ios_base::sync_with_stdio(23^23);cin.tie(NULL);
cin>>n>>k;
for(int i=1;i<=n;i++){
cin>>loc[i];
}
for(int i=1;i<=n;i++){
cin>>t[i];
}
for(int i=0;i<=n;i++){
for(int j=i+1;j<=n+1;j++){
for(int l=0;l<=n;l++){
for(int r=0;r<2;r++){
dp[i][j][l][r]=1e9+1;
}
}
}
}
dp[0][n+1][0][0]=0;
int ans=0;
for(int res=0;res<=n;res++){
for(int l=0;l<=n;l++){
for(int r=n+1;r>l;r--){
for(int a=0;a<2;a++){
if(dp[l][r][res][a]==1e9+1)continue;
if(r-l==1){
ans=max(ans,res);
continue;
}
if(a==0){
int res2=res;
if(t[l+1]>=dp[l][r][res][a]+loc[l+1]-loc[l]){
res2++;
}
dp[l+1][r][res2][a]=min(dp[l][r][res][a]+loc[l+1]-loc[l],dp[l+1][r][res2][a]);
res2=res;
if(t[r-1]>=dp[l][r][res][a]+loc[l]+k-loc[r-1]){
res2++;
}
dp[l][r-1][res2][1]=min(dp[l][r][res][a]+loc[l]+k-loc[r-1],dp[l][r-1][res2][1]);
}
else{
int res2=res;
if(t[l+1]>=dp[l][r][res][a]+loc[l+1]+k-loc[r]){
res2++;
}
dp[l+1][r][res2][0]=min(dp[l][r][res][a]+loc[l+1]+k-loc[r],dp[l+1][r][res2][0]);
res2=res;
if(t[r-1]>=dp[l][r][res][a]+loc[r]-loc[r-1]){
res2++;
}
dp[l][r-1][res2][a]=min(dp[l][r][res][a]+loc[r]-loc[r-1],dp[l][r-1][res2][a]);
}
}
}
}
}
cout<<ans<<endl;
}
