#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define sc second
#define pb push_back
#define in insert
const ll MXT = 2000000000000;
ll dp[201][201][201][2];
int32_t main () {
ios::sync_with_stdio(false);
cin.tie(nullptr);
ll n , l; cin>>n>>l;
ll a[n + 2],t[n + 2];
for (int i = 1; i <= n; i++)
cin>>a[i];
for (int i = 1; i <= n; i++)
cin>>t[i];
for(int i = 0; i <= n + 1; i++)
for(int j = 0; j <= n + 1; j++)
for(int k = 0; k <= n + 1; k++)
dp[i][j][k][0] = dp[i][j][k][1] = MXT;
dp[n + 1][0][0][0] = dp[n + 1][0][0][1] = 0;
a[0] = 0 ;
a[n + 1] = l;
for(int i = n + 1; i > 1; i--){
for (int j = 0; j <= i; j++) {
for(int k = 0; k <= n; k++) {
ll mn = dp[i][j][k][0] + a[j + 1] - a[j];
mn = min(mn , dp[i][j][k][1] + l - a[i] + a[j + 1]);
if (mn <= t[j + 1]) dp[i][j + 1][k + 1][0] = min(mn , dp[i][j + 1][k + 1][0]);
else dp[i][j + 1][k][0] = min(mn , dp[i][j + 1][k][0]);
mn = dp[i][j][k][0] + a[j] + l - a[i - 1];
mn = min(mn , dp[i][j][k][1] - a[i - 1] + a[i]);
if (mn <= t[i - 1]) dp[i - 1][j][k + 1][1] = min(mn , dp[i - 1][j][k + 1][1]);
else dp[i - 1][j][k][1] = min(mn , dp[i - 1][j][k][1]);
}
}
}
ll ans = 0;
for (int j = 0; j <= n; j++) {
for (ll k = 1; k <= n; k++) {
if(dp[j + 1][j][k][0] != MXT) ans = max(k, ans);
if(dp[j + 1][j][k][1] != MXT) ans = max(k, ans);
}
}
cout<<ans;
}
