#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
ll L;
cin >> n >> L;
vector<ll> x(n), t(n);
for(ll &i : x)
cin >> i;
for(ll &i : t)
cin >> i;
const ll inf = (1ll << 60);
vector dp(n + 1, vector(n + 1, vector(2, vector(n + 1, inf))));
dp[0][0][0][0] = dp[0][0][1][0] = 0;
auto left = [&](int a) -> ll {
return x[n - a] - L;
};
auto right = [&](int b) -> ll {
return x[b - 1];
};
auto cur_pos = [&](int a, int b, int side) -> ll {
if(!side) {
if(!a) return 0;
return left(a);
} else {
if(!b) return 0;
return right(b);
}
};
auto umin = [](ll& a, ll b) {
if(a > b) a = b;
};
for(int a = 0; a <= n; ++a) {
for(int b = 0; b <= n; ++b) {
for(int side = 0; side < 2; ++side) {
for(int got = 0; got <= n; ++got) {
ll cur = dp[a][b][side][got];
if(cur == inf) continue;
ll from = cur_pos(a, b, side);
//left
if(a < n && a + b < n) {
int na = a + 1;
int id = n - na;
ll to = left(na);
ll nt = cur + abs(from - to);
umin(dp[na][b][0][got + (nt <= t[id])], nt);
}
//right
if(b < n && b + a < n) {
int nb = b + 1;
int id = nb - 1;
ll to = right(nb);
ll nt = cur + abs(from - to);
umin(dp[a][nb][1][got + (nt <= t[id])], nt);
}
}
}
}
}
int ans = 0;
for(int a = 0; a <= n; ++a) {
for(int b = 0; b <= n; ++b) {
for(int side = 0; side < 2; ++side) {
for(int got = 0; got <= n; ++got) {
if(dp[a][b][side][got] != inf) {
ans = max(ans, got);
}
}
}
}
}
cout << ans;
return 0;
}
