#include<bits/stdc++.h>
using namespace std;
/*for ordered_set
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<pair<int,int>, null_type,less<pair<int,int>>, rb_tree_tag,tree_order_statistics_node_update>
*/
const long long INFll = (long long) 1e18 + 10;
const int INFii = (int) 1e9 + 10;
typedef long long ll;
typedef int ii;
typedef long double dbl;
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
#define maxn 220
ll n, L, x[2*maxn], t[2*maxn], dist[2*maxn][2*maxn], dp[2*maxn][2*maxn][maxn][2];
void solve() {
cin >> n >> L;
for(ii i = 1; i <= n; i++) {
cin >> x[i];
}
for(ii i = 1; i <= n; i++) {
cin >> t[i];
}
for(ii i = 1; i <= n; i++) {
x[i+n] = x[i];
t[i+n] = t[i];
}
x[0] = 0;
for(ii i = 0; i <= 2*n; i++) {
for(ii j = 0; j <= 2*n; j++) {
dist[i][j] = INFll;
ll x1 = x[i];
ll x2 = x[j];
dist[i][j] = min(dist[i][j],abs(x2-x1));
x1+= L;
dist[i][j] = min(dist[i][j],abs(x2-x1));
x1-= L;
x2+= L;
dist[i][j] = min(dist[i][j],abs(x2-x1));
x2-= L;
for(ii k = 0; k <= n; k++) {
dp[i][j][k][0] = dp[i][j][k][1] = INFll;
}
}
}
//sz = size-1 of (l,r)
//l = begin
//r = end
//k = qtd things catch in (l,r)
//p = 0 -> l; 1 -> r
//dp[l][r][k][p] -> min time for cover the interval (l,r)
// with ans = k now in (0->l, 1->r)
for(ii i = 1; i <= 2*n; i++) {
ii k = 0;
if(dist[i][0] <= t[i]) {
k++;
}
dp[i][i][k][0] = dp[i][i][k][1] = dist[i][0];
}
for(ii sz = 0; sz < n; sz++) {
for(ii l = 1; l+sz <= 2*n; l++) {
ii r = l+sz;
for(ii k = 0; k <= n; k++) {
dp[l][r][k][0] = min(dp[l][r][k][0],dp[l][r][k][1]+dist[l][r]);
dp[l][r][k][1] = min(dp[l][r][k][1],dp[l][r][k][0]+dist[l][r]);
for(ii p = 0; p <= 1; p++) {
ll tmin = dp[l][r][k][p];
if(p == 0 && l-1 >= 1) {
//pos = l
ii l1 = l-1;
ii r1 = r;
ii p1 = 0;
ll tmin1 = dist[l][l1] + tmin;
ii k1 = k;
if(tmin1 <= t[l1]) k1++;
dp[l1][r1][k1][p1] = min(dp[l1][r1][k1][p1],tmin1);
}
if(p == 1 && r+1 <= 2*n) {
//pos = l
ii l1 = l;
ii r1 = r+1;
ii p1 = 1;
ll tmin1 = dist[r][r1] + tmin;
ii k1 = k;
if(tmin1 <= t[r1]) k1++;
dp[l1][r1][k1][p1] = min(dp[l1][r1][k1][p1],tmin1);
}
}
}
}
}
ii ans = 0;
for(ii sz = 0; sz < n; sz++) {
for(ii l = 1; l+sz <= 2*n; l++) {
ii r = l+sz;
for(ii k = 0; k <= n; k++) {
for(ii p = 0; p <= 1; p++) {
if(dp[l][r][k][p] != INFll) {
// cout << l << " " << r << " " << k << " " << p << " == " << dp[l][r][k][p] << endl;
ans = max(ans,k);
}
}
}
}
}
cout << ans << endl;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
// freopen("in.in", "r", stdin);
//freopen("out.out", "w", stdout);
ii tt = 1;
// cin >> tt;
while(tt--) solve();
}
