#include <algorithm>
#include <iostream>
using namespace std;
const int N = 200;
const int INF = 0x3f3f3f3f;
int aa[N], tt[N], dp[N + 1][N + 1][N + 1], dq[N + 1][N + 1][N + 1];
int main() {
ios_base::sync_with_stdio(false), cin.tie(NULL);
int n, a_; cin >> n >> a_;
for (int i = 0; i < n; i++)
cin >> aa[i];
for (int i = 0; i < n; i++)
cin >> tt[i];
for (int l = 0; l <= n; l++)
for (int r = 0; l + r <= n; r++)
for (int k = 0; k <= n; k++)
dp[l][r][k] = dq[l][r][k] = INF;
dp[0][0][0] = dq[0][0][0] = 0;
for (int l = 0; l < n; l++)
for (int r = 0; l + r < n; r++)
for (int k = 0; k < n; k++) {
dq[l][r][k] = min(dq[l][r][k], dp[l][r][k] + (l ? aa[l - 1] : 0) + (r ? a_ - aa[n - r] : 0));
dp[l][r][k] = min(dp[l][r][k], dq[l][r][k] + (l ? aa[l - 1] : 0) + (r ? a_ - aa[n - r] : 0));
int t = dp[l][r][k] + aa[l] - (l ? aa[l - 1] : 0), k_ = k + (t <= tt[l]);
dp[l + 1][r][k_] = min(dp[l + 1][r][k_], t);
t = dq[l][r][k] + (r ? aa[n - r] : a_) - aa[n - 1 - r], k_ = k + (t <= tt[n - 1 - r]);
dq[l][r + 1][k_] = min(dq[l][r + 1][k_], t);
}
int ans = 0;
for (int l = 0; l <= n; l++)
for (int r = 0; l + r <= n; r++)
for (int k = 0; k <= n; k++)
if (dp[l][r][k] < INF || dq[l][r][k] < INF)
ans = max(ans, k);
cout << ans << '\n';
return 0;
}
