#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n, h;
  cin >> n >> h;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  vector<ll> b(n);
  rep(i, n) cin >> b[i];
  ll sum_a = 0, sum_b = 0, now = 0, r = 0, ans = 0;
  rep(l, n) {
    while (now <= h) {
      ans = max(ans, sum_a);
      if (r == n)
        break;
      sum_a += a[r];
      sum_b += b[r];
      now += b[r] * (r - l + 1);
      r += 1;
    }
    now -= sum_b;
    sum_b -= b[l];
    sum_a -= a[l];
  }
  cout << ans << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}