#include <bits/stdc++.h>
using namespace std;
const int N = 205;
const long long INF = 1E18 + 7;
int n, l, cur, le, ri, ans = 0, x[N], d[N];
long long dst, dp[N][N][N][2];
void mini(long long &cur, long long tmp) {
if (tmp < cur) {
cur = tmp;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> l;
for (int i = 1; i <= n; i++) {
cin >> x[i];
}
for (int i = 1; i <= n; i++) {
cin >> d[i];
}
n++;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
for (int k = 0; k < n; k++) {
dp[i][j][k][0] = dp[i][j][k][1] = INF;
}
}
}
dp[0][0][0][0] = 0;
for (int k = 0; k < n; k++) {
for (int len = 0; len < n; len++) {
for (int i = 0; i < n; i++) {
for (int t = 0; t < 2; t++) {
if (dp[i][len][k][t] == INF) {
continue;
}
cur = (t == 0 ? i : (i + len) % n);
le = (i + n - 1) % n;
ri = (i + len + 1) % n;
dst = min(l - abs(x[cur] - x[le]), abs(x[cur] - x[le])) + dp[i][len][k][t];
mini(dp[le][len + 1][k + (dst <= d[le])][0], dst);
dp[le][len + 1][k + (dst <= d[le])][0] = min(dp[le][len + 1][k + (dst <= d[le])][0], dst);
dst = min(l - abs(x[cur] - x[ri]), abs(x[cur] - x[ri])) + dp[i][len][k][t];
mini(dp[i][len + 1][k + (dst <= d[ri])][1], dst);
ans = max(ans, k);
}
}
}
}
cout << ans;
}
