#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr int N = 205;
int n, m;
ll x[2*N], t[2*N], dp[N][N][N][2];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m;
for(int i = 0; i < n; i++) {
cin >> x[i];
}
for(int i = 0; i < n; i++) {
cin >> t[i];
}
auto dist = [&](int now, int next) {
int d = min(m - now, now);
d += min(next, m - next);
return min(abs(now - next), d);
};
x[n] = 0;
t[n] = 1e9;
for(int i = 1; i <= n; i++) {
x[n + i] = x[i - 1];
t[n + i] = t[i - 1];
}
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] = 1e18;
dp[0][0][0][0] = dp[0][0][0][1] = 0;
for(int l = 0; l <= n; l++) {
for(int r = 0; l + r < n; r++) {
if(l == n || r == n) continue;
for(int cnt = 0; cnt <= l + r; cnt++) {
for(int dir = 0; dir <= 1; dir++) {
if(dp[l][r][cnt][dir] == 1e18) continue;
int now = dir ? x[n + r] : x[n - l];
int next = x[n + r + 1];
ll tim = t[n + r + 1];
ll tum = dp[l][r][cnt][dir] + dist(now, next);
dp[l][r + 1][cnt + (tum <= tim)][1] = min(dp[l][r + 1][cnt + (tum <= tim)][1], tum);
next = x[n - l - 1];
tim = t[n - l - 1];
tum = dp[l][r][cnt][dir] + dist(now, next);
dp[l + 1][r][cnt + (tum <= tim)][0] = min(dp[l + 1][r][cnt + (tum <= tim)][0], tum);
}
}
}
}
int ans = 0;
for(int l = 0; l <= n; l++) for(int r = 0; r <= n; r++) for(int cnt = 0; cnt <= l + r; cnt++) {
if(dp[l][r][cnt][0] < 1e18 || dp[l][r][cnt][1] < 1e18) ans = max(ans, cnt);
}
cout << ans;
return 0;
}
