#include <bits/stdc++.h> using namespace std; using ll = long long; ll INF = 1e18; int main() { ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); ll n, dist; cin >> n >> dist; vector<ll> s(n), z(n); ll las = 0; for (ll i = 0; i < n; i++) { cin >> s[i]; las = s[i]; } vector<ll> v2(n); v2[0] = dist - las; for (ll i = 1; i < n; i++) { v2[i] = s[n - i] - s[n - i - 1]; } for (ll i = n - 1; i >= 1; i--) { s[i] = s[i] - s[i - 1]; } for (ll i = 0; i < n; i++) { cin >> z[i]; } auto v1 = s; vector<ll> sum_l(n + 1); vector<ll> sum_r(n + 1); vector<ll> time_l(n); vector<ll> time_r(n); for (ll i = 0; i < n; i++) { sum_l[i + 1] = sum_l[i] + v1[i]; } for (ll i = 0; i < n; i++) { time_l[i] = z[i]; } time_r = time_l; reverse(time_r.begin(), time_r.end()); for (ll i = 0; i < n; i++) { sum_r[i + 1] = sum_r[i] + v2[i]; } vector<vector<vector<vector<ll>>>> dp(n + 1, vector<vector<vector<ll>>>(n + 1, vector<vector<ll>>(n + 1, vector<ll>(2, INF)))); dp[0][0][0][0] = 0; dp[0][0][0][1] = 0; ll ans = 0; for (ll i = 0; i < n; i++) { for (ll j = 0; j <= i; j++) { for (ll e = 0; e <= i; e++) { ll l = j; ll r = i - j; ll tm = dp[l][r][e][0]; ll all = sum_l[l] + sum_r[r]; dp[l + 1][r][e][0] = min(dp[l + 1][r][e][0], tm + v1[l]); if (tm + v1[l] <= time_l[l]) { dp[l + 1][r][e + 1][0] = min(dp[l + 1][r][e + 1][0], tm + v1[l]); } dp[l + 1][r][e][1] = min(dp[l + 1][r][e][1], tm + v1[l] + v1[l] + all); if (tm + v1[l] <= time_l[l]) { dp[l + 1][r][e + 1][1] = min(dp[l + 1][r][e + 1][1], tm + v1[l] + v1[l] + all); } tm = dp[l][r][e][1]; dp[l][r + 1][e][1] = min(dp[l][r + 1][e][1], tm + v2[r]); if (tm + v2[r] <= time_r[r]) { dp[l][r + 1][e + 1][1] = min(dp[l][r + 1][e + 1][1], tm + v2[r]); } dp[l][r + 1][e][0] = min(dp[l][r + 1][e][0], tm + v2[r] + v2[r] + all); if (tm + v2[r] <= time_r[r]) { dp[l][r + 1][e + 1][0] = min(dp[l][r + 1][e + 1][0], tm + v2[r] + v2[r] + all); } } } } for (ll i = 0; i <= n; i++) { for (ll j = 0; j <= i; j++) { for (ll e = 0; e <= i; e++) { ll l = j; ll r = i - j; if (dp[l][r][e][0] < INF) { ans = max(ans, e); } if (dp[l][r][e][1] < INF) { ans = max(ans, e); } } } } cout << ans; }