#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
const int N=205;
const ll INF=1e18;
void chmn(ll &x,ll y){x=min(x,y);}
int n;ll L;
ll X[2*N],T[2*N];
ll dp[2][2*N][2*N][N];
ll dist(int i,int j){
return min(abs(X[i]-X[j]),L-abs(X[i]-X[j]));
}
int main(){
scanf("%i%lld",&n,&L);
for(int i=1;i<=n;i++) scanf("%lld",&X[i]);
for(int i=1;i<=n;i++) scanf("%lld",&T[i]);
n++;T[0]=-1;
for(int i=n;i<2*n;i++)X[i]=X[i-n],T[i]=T[i-n];
for(int l=0;l<2*n;l++){
for(int r=0;r<2*n;r++){
for(int k=0;k<=n;k++){
dp[0][l][r][k]=dp[1][l][r][k]=INF;
}
}
}
dp[0][n][n][0]=dp[1][n][n][0]=0;
int res=0;
for(int l=n;l>=0;l--){
for(int r=n;r<=n+l-1;r++){
for(int k=0;k<=n;k++){
chmn(dp[0][l][r][k],dp[0][l+1][r][k]+dist(l,l+1));
if(k>0&&dp[0][l+1][r][k-1]+dist(l,l+1)<=T[l])chmn(dp[0][l][r][k],dp[0][l+1][r][k-1]+dist(l,l+1));
chmn(dp[0][l][r][k],dp[1][l+1][r][k]+dist(l,r));
if(k>0&&dp[1][l+1][r][k-1]+dist(l,r)<=T[l])chmn(dp[0][l][r][k],dp[1][l+1][r][k-1]+dist(l,r));
if(dp[0][l][r][k]<INF)res=max(res,k);
chmn(dp[1][l][r][k],dp[0][l][r-1][k]+dist(r,l));
if(k>0&&dp[0][l][r-1][k-1]+dist(r,l)<=T[r])chmn(dp[1][l][r][k],dp[0][l][r-1][k-1]+dist(r,l));
chmn(dp[1][l][r][k],dp[1][l][r-1][k]+dist(r,r-1));
if(k>0&&dp[1][l][r-1][k-1]+dist(r,r-1)<=T[r])chmn(dp[1][l][r][k],dp[1][l][r-1][k-1]+dist(r,r-1));
if(dp[1][l][r][k]<INF)res=max(res,k);
}
}
}
printf("%i\n",res);
return 0;
}
