#include <bits/stdc++.h>
using namespace std;
const int N = 205;
int n, l, x[N], t[N];
void solve(void) {
cin >> n >> l;
for (int i = 1; i <= n; i++) cin >> x[i];
for (int i = 1; i <= n; i++) cin >> t[i];
int ans = 0, cur = 0, res = 0;
// I. CW
cur = res = 0;
for (int i = 1; i <= n; i++) {
cur += x[i];
res += cur <= t[i];
int cur2 = 2 * cur, res2 = res;
for (int j = n; j > i; j--) {
res2 += (cur2 + l - x[j]) <= t[j];
}
ans = max(ans, res2);
}
ans = max(ans, res);
// II. CCW;
res = 0;
for (int i = n; i; i--) {
res += (l - x[i]) <= t[i];
int cur2 = 2 * (l - x[i]), res2 = res;
for (int j = 1; j < i; j++) {
res2 += (cur2 + x[j]) <= t[j];
}
ans = max(ans, res2);
}
ans = max(ans, res);
cout << ans;
}
signed main(void) {
ios::sync_with_stdio(false); cin.tie(nullptr);
int T = 1;// cin >> T;
while (T--) solve();
return 0;
}
