#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 1e18;
vector<vector<vector<int>>> dp[2];
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int n, l;
cin >> n >> l;
vector<int> x(n), t(n);
for (auto& el : x)
cin >> el;
for (auto& el : t)
cin >> el;
auto dist = [&](int x1, int x2) {
int res = (x1 - x2 + l) % l;
res = min(res, (x2 - x1 + l) % l);
return res;
};
dp[0].resize(n + 1, vector<vector<int>>(n + 1, vector<int>(n + 1, INF)));
dp[1].resize(n + 1, vector<vector<int>>(n + 1, vector<int>(n + 1, INF)));
dp[0][0][0][0] = 0;
dp[1][0][0][0] = 0;
dp[0][1][0][0] = dist(0, x[0]);
if (dp[0][1][0][0] <= t[0])
dp[0][1][0][1] = dp[0][1][0][0];
dp[1][0][1][0] = dist(0, x[n - 1]);
if (dp[1][0][1][0] <= t[n - 1])
dp[1][0][1][1] = dp[1][0][1][0];
for (int ln = 2; ln <= n; ++ln) {
for (int l = 0; l <= ln; ++l) {
int r = ln - l;
if (l != 0) {
for (int prevcnt = 0; prevcnt < ln; ++prevcnt) {
if (l - 1 != 0)
dp[0][l][r][prevcnt] = min(dp[0][l][r][prevcnt], dp[0][l - 1][r][prevcnt] + dist(x[l - 1], x[l - 2]));
if (r != 0)
dp[0][l][r][prevcnt] = min(dp[0][l][r][prevcnt], dp[1][l - 1][r][prevcnt] + dist(x[l - 1], x[n - r]));
}
for (int curcnt = ln ; curcnt > 0; --curcnt)
if (dp[0][l][r][curcnt - 1] <= t[l - 1])
dp[0][l][r][curcnt] = min(dp[0][l][r][curcnt], dp[0][l][r][curcnt - 1]);
}
if (r != 0) {
for (int prevcnt = 0; prevcnt < ln; ++prevcnt) {
if (r - 1 != 0)
dp[1][l][r][prevcnt] = min(dp[1][l][r][prevcnt], dp[1][l][r - 1][prevcnt] + dist(x[n - r], x[n - r + 1]));
if (l != 0)
dp[1][l][r][prevcnt] = min(dp[1][l][r][prevcnt], dp[0][l][r - 1][prevcnt] + dist(x[n - r], x[l - 1]));
}
for (int curcnt = ln ; curcnt > 0; --curcnt)
if (dp[1][l][r][curcnt - 1] <= t[n - r])
dp[1][l][r][curcnt] = min(dp[1][l][r][curcnt], dp[1][l][r][curcnt - 1]);
}
}
}
for (int curcnt = n; curcnt > 0; --curcnt) {
for (int l = 0; l <= n; ++l) {
int r = n - l;
if (dp[0][l][r][curcnt] != INF) {
cout << curcnt;
return 0;
}
if (dp[1][l][r][curcnt] != INF) {
cout << curcnt;
return 0;
}
}
}
cout << 0;
return 0;
}
