#include<iostream>
#include<vector>
#include<set>
#include<algorithm>
using namespace std;
#define ll long long
#define mp make_pair
#define pii pair<ll,ll>
#define inf (ll)1e15
#define endl "\n"
#define out(x) cout<< #x << " = " << x << endl
int n;
ll L,X[206],T[206];
ll dp[206][206][206][2]; // 已經看過區間(i,j)，拿到了k個stamp，目前人在最左或最右，的最小時間
int goleft(int x){
return x-1 ? x-1:n;
}
int goright(int x){
return x==n ? 1:x+1;
}
ll dist(int i,int j){
if (i<j) return X[j] - X[i];
return X[j] - X[i] + L;
}
void chmin(ll &a, ll b){
a = min(a,b);
}
signed main(){
ios::sync_with_stdio(false); cin.tie(0);
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 i=1;i<=n;i++) for (int j=1;j<=n;j++) for (int k=0;k<=n;k++) dp[i][j][k][0] = dp[i][j][k][1] = inf;
if (X[1] <= T[1]) dp[1][1][1][0] = dp[1][1][1][1] = X[1];
else dp[1][1][0][0] = dp[1][1][0][1] = X[1];
if (L-X[n] <= T[n]) dp[n][n][1][0] = dp[n][n][1][1] = L-X[n];
else dp[n][n][0][0] = dp[n][n][0][1] = L-X[n];
for (int d=0;d<n;d++) for (int i=1;i<=n;i++) for (int k=0;k<=d+1;k++){
int j = i+d > n ? i+d-n : i+d;
ll nowtime = dp[i][j][k][0];
if (nowtime + dist(goleft(i), i) <= T[goleft(i)]){
chmin(dp[goleft(i)][j][k+1][0], nowtime + dist(goleft(i), i));
}
else chmin(dp[goleft(i)][j][k][0], nowtime + dist(goleft(i), i));
if (nowtime + dist(i,goright(j)) <= T[goright(j)]){
chmin(dp[i][goright(j)][k+1][1], nowtime + dist(i, goright(j)));
}
else chmin(dp[i][goright(j)][k][1], nowtime + dist(i, goright(j)));
nowtime = dp[i][j][k][1];
if (nowtime + dist(goleft(i), j) <= T[goleft(i)]){
chmin(dp[goleft(i)][j][k+1][0], nowtime + dist(goleft(i), j));
}
else chmin(dp[goleft(i)][j][k][0], nowtime + dist(goleft(i), j));
if (nowtime + dist(j, goright(j)) <= T[goright(j)]){
chmin(dp[i][goright(j)][k+1][1], nowtime + dist(j, goright(j)));
}
else chmin(dp[i][goright(j)][k][1], nowtime + dist(j, goright(j)));
}
/*for (int i=1;i<=n;i++) for (int j=1;j<=n;j++){
int d = j-i < 0 ? j-i+n : j-i;
for (int k=0;k<=d;k++) ;//cout<<i<<" "<<j<<" "<<k<<" "<<dp[i][j][k][0]<<" "<<dp[i][j][k][1]<<endl;
}*/
int best = 0;
for (int k=0;k<n;k++){
for (int i=1;i<=n;i++) for (int j=1;j<=n;j++) {
int d = j-i < 0 ? j-i+n : j-i;
if (k>d) continue;
if (dp[i][j][k][0] < inf || dp[i][j][k][1] < inf) best = k;
}
}
// 全部可選的特判？
for (int i=1;i<=n;i++){
if (dp[i][goleft(i)][n][0] < inf || dp[i][goleft(i)][n][1] < inf) best = n;
if (dp[i][goright(i)][n][0] < inf || dp[i][goright(i)][n][1] < inf) best = n;
}
cout<<best<<endl;
}
