#include <bits/stdc++.h>
#define _CRT_SECURE_NO_WARNINGS
using namespace std;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define sort_uniq(x) sort(all(x)), uniq(x);
#define ll long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define V vector
#define V2dll V<V<ll>>
#define V2dint V<V<int>>
#define V2dchar V<V<char>>
#define V2dbool V<V<bool>>
#define V3dll V<V<V<ll>>>
#define V3dint V<V<V<int>>>
#define V3dchar V<V<V<char>>>
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define eb emplace_back
#define FASTIO ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define blt __builtin_popcount
#define clr(x) x.clear()
#define ff first
#define ss second
#define popf pop_front
#define popb pop_back
#define sz(x) int(x.size())
#define rep(a,b,c,d) for(int a = b;a <= c; a += d)
#define repl(a,b,c,d) for(int a = b; a >= c; a -= d)
mt19937_64 rng(chrono::steady_clock().now().time_since_epoch().count());
const int N = 205;
const ll INFLL = 1e18;
ll dp[N][N][N][2];
ll x[N];
ll t[N];
void prec() {
rep(i, 0, N - 1, 1) {
rep(j, 0, N - 1, 1) {
rep(k, 0, N - 1, 1) {
rep(ms, 0, 1, 1) {
dp[i][j][k][ms] = INFLL;
}
}
}
}
}
int main()
{
FASTIO
prec();
int n; cin >> n;
ll l; cin >> l;
rep(i, 1, n, 1) cin >> x[i];
rep(i, 1, n, 1) cin >> t[i];
x[0] = 0;
x[n + 1] = l;
dp[0][n + 1][0][0] = dp[0][n + 1][0][1] = 0;
rep(i, 0, n, 1) {
repl(j, n + 1, max(i + 1, 1), 1) {
rep(k, 0, n, 1) {
if (i == j - 1) continue;
ll tim0 = dp[i][j][k][0];
ll tim1 = dp[i][j][k][1];
if (tim0 != INFLL) {
ll nt = tim0 + x[i + 1] - x[i];
int nk = k + (nt <= t[i + 1] ? 1 : 0);
dp[i + 1][j][nk][0] = min(dp[i + 1][j][nk][0], nt);
}
if (tim1 != INFLL) {
ll nt = tim1 + l - x[j] + x[i + 1];
int nk = k + (nt <= t[i + 1] ? 1 : 0);
dp[i + 1][j][nk][0] = min(dp[i + 1][j][nk][0], nt);
}
if (tim0 != INFLL) {
ll nt = tim0 + x[i] + l - x[j - 1];
int nk = k + (nt <= t[j - 1] ? 1 : 0);
dp[i][j - 1][nk][1] = min(dp[i][j - 1][nk][1], nt);
}
if (tim1 != INFLL) {
ll nt = tim1 + x[j] - x[j - 1];
int nk = k + (nt <= t[j - 1] ? 1 : 0);
dp[i][j - 1][nk][1] = min(dp[i][j - 1][nk][1], nt);
}
}
}
}
int ans = 0;
rep(i, 0, n, 1) {
repl(j, n + 1, max(i, 1), 1) {
rep(k, 0, n, 1) {
rep(it, 0, 1, 1) {
if (dp[i][j][k][it] < INFLL) {
ans = max(ans, k);
}
}
}
}
}
cout << ans << "\n";
return 0;
}
