#include <bits/stdc++.h>
#define int long long
#define IO ios::sync_with_stdio(0), cin.tie(0)
#define FOR(i, a, b) for (int i = a, I = b; i <= I; i++)
using namespace std;
using pii = pair<int, int>;
void dbg() {;}
template<class T, class ...U>
void dbg(T a, U ...b) { cout << a << " "; dbg(b...); }
void ent() { cout << "\n"; }
const int INF = 1e17;
const int N = 205;
int a[N], t[N];
int dp[2][N][N][N];
signed main() {
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
IO;
int n, tot;
cin >> n >> tot;
FOR(i, 1, n) cin >> a[i];
FOR(i, 1, n) cin >> t[i];
int ans = 0;
fill(&dp[0][0][0][0], &dp[0][0][0][0] + 2 * N * N * N, INF);
dp[0][0][0][n] = 0;
for (int i = 0; i <= n; i++) {
for (int r = n; r >= 1; r--) {
// Left : 0
for (int l = 1; l <= r; l++) {
int ti;
if (i) {
ti = dp[0][i - 1][l - 1][r] + (a[l] - a[l - 1]);
if (ti <= t[l])
dp[0][i][l][r] = min(dp[0][i][l][r], ti);
if (r + 1 <= n) {
ti = dp[1][i - 1][l][r + 1] + (tot - a[r + 1] + a[l] - 0);
if (ti <= t[l])
dp[0][i][l][r] = min(dp[0][i][l][r], ti);
}
}
ti = dp[0][i][l - 1][r] + (a[l] - a[l - 1]);
dp[0][i][l][r] = min(dp[0][i][l][r], ti);
if (r + 1 <= n) {
ti = dp[1][i][l][r + 1] + (tot - a[r + 1] + a[l] - 0);
dp[0][i][l][r] = min(dp[0][i][l][r], ti);
}
if (dp[0][i][l][r] < INF) {
// dbg(0, i, l, r, ':', dp[0][i][l][r]), ent();
ans = max(ans, i);
}
}
// Right : 1
for (int l = 1; l <= r; l++) {
int ti;
if (i) {
ti = dp[0][i - 1][l - 1][r] + (a[l - 1] - 0 + tot - a[r]);
if (ti <= t[r])
dp[1][i][l][r] = min(dp[1][i][l][r], ti);
ti = dp[1][i - 1][l][r + 1] + (a[r + 1] - a[r]);
if (ti <= t[r])
dp[1][i][l][r] = min(dp[1][i][l][r], ti);
}
ti = dp[0][i][l - 1][r] + (a[l - 1] - 0 + tot - a[r]);
dp[1][i][l][r] = min(dp[1][i][l][r], ti);
if (r + 1 <= n) {
ti = dp[1][i][l][r + 1] + (a[r + 1] - a[r]);
dp[1][i][l][r] = min(dp[1][i][l][r], ti);
}
if (dp[1][i][l][r] < INF) {
// dbg(1, i, l, r, ':', dp[1][i][l][r]), ent();
ans = max(ans, i);
}
}
}
}
cout << ans << "\n";
return 0;
}
