#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N = 205;
ll n, l;
ll cl[N], ccl[N], t[N];
void read() {
cin >> n >> l;
for(int i = 0; i < n; i++) {
cin >> cl[i];
ccl[i] = l - cl[i];
}
for(int i = 0; i < n; i++)
cin >> t[i];
}
void solve() {
ll ans = 0, dist = 0, dist2 = 0, cnt = 0;
for(int i = 0; i < n; i++) {
//go cl first
dist = dist2 = cnt = 0;
for(int j = 0; j <= i; j++) {
dist = cl[j];
if(t[j] >= dist) cnt++;
}
if(i < n-1) {
for(int j = n-1; j > i; j--) {
dist2 = ccl[j];
if(t[j] >= 2*dist + dist2) cnt++;
}
}
ans = max(ans, cnt);
//go ccl first
dist = dist2 = cnt = 0;
for(int j = n-1; j >= i; j--) {
dist2 = ccl[j];
if(t[j] >= dist2) cnt++;
}
if(i > 0) {
for(int j = 0; j < i; j++) {
dist = cl[j];
if(t[j] >= 2*dist2 + dist) cnt++;
}
}
ans = max(ans, cnt);
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
read();
solve();
return 0;
}
