#include <bits/stdc++.h>
#define int long long
#define pb push_back
using namespace std;
const int N=310;
const int inf=1e18;
const int mod=1e9+7;
int x[N],t[N];
int dp[N][N][2][N];
signed main() {
ios_base::sync_with_stdio(NULL);
cin.tie(NULL);
int T=1;
// cin>>T;
while(T--) {
int n,l;
cin>>n>>l;
for(int i=1;i<=n;i++) cin>>x[i];
for(int i=1;i<=n;i++) cin>>t[i];
x[n+1] = l;
for(int i=0;i<=n+1;i++) {
for(int j=0;j<=n+1;j++) {
for(int k=0;k<=n;k++) {
dp[i][j][0][k]=inf;
dp[i][j][1][k]=inf;
}
}
}
dp[n + 1][0][1][0]=dp[n + 1][0][0][0]=0;
for(int i=n+1;i>0;i--) {
for(int j=0;j<i;j++) {
for(int k=0;k<=n;k++) {
if(i<=n) {
if(k > 0 && dp[i+1][j][0][k-1]<inf && dp[i+1][j][0][k-1]+abs(x[i + 1]-x[i])<=t[i]) {
dp[i][j][0][k]=min(dp[i][j][0][k], dp[i+1][j][0][k-1]+abs(x[i + 1]-x[i]));
}
dp[i][j][0][k] = min({inf, dp[i][j][0][k], dp[i + 1][j][0][k] + abs(x[i + 1]-x[i])});
if(k > 0 && dp[i+1][j][1][k-1]<inf && dp[i+1][j][1][k-1]+l-x[i]+x[j]<=t[i]) {
dp[i][j][0][k]=min(dp[i][j][0][k],dp[i+1][j][1][k-1]+l-x[i]+x[j]);
}
dp[i][j][0][k] = min({inf, dp[i][j][0][k], dp[i + 1][j][1][k] + l-x[i]+x[j]});
}
if(j>0) {
if(k > 0 && dp[i][j-1][1][k-1]<inf && dp[i][j-1][1][k-1]+abs(x[j - 1]-x[j])<=t[j]) {
dp[i][j][1][k]=min(dp[i][j][1][k], dp[i][j-1][1][k-1]+abs(x[j - 1]-x[j]));
}
dp[i][j][1][k] = min({inf, dp[i][j][1][k], dp[i][j - 1][1][k] + abs(x[j - 1]-x[j])});
if(k > 0 && dp[i][j-1][0][k-1]<inf && dp[i][j-1][0][k-1]+l-x[i]+x[j]<=t[j]) {
dp[i][j][1][k]=min(dp[i][j][1][k],dp[i][j-1][0][k-1]+l-x[i]+x[j]);
}
dp[i][j][1][k] = min({inf, dp[i][j][1][k], dp[i][j - 1][0][k] + l-x[i]+x[j]});
}
}
}
}
// cout<<dp[5][3][1][4]<<'\n';
int ans=0;
for(int i=n+1;i>=0;i--) {
for(int j=0;j<=n+1;j++) {
for(int k=1;k<=n;k++) {
if(dp[i][j][0][k]<inf || dp[i][j][1][k]<inf) {
ans=max(ans,k);
//if(k==5)cout<<i<<' '<<j<<"\n";
}
}
}
}
cout<<ans;
}
}
