#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using mint = modint998244353;

int main() {
  ll N, H; cin >> N >> H;
  vector<ll> A(N), B(N);
  for (int i = 0; i < N; i++) cin >> A[i];
  for (int i = 0; i < N; i++) cin >> B[i];
  vector<ll> sumB(N + 1);
  for (int i = 0; i < N; i++) {
    sumB[i + 1] = sumB[i] + B[i];
  }
  int r = 0;
  ll ans = 0, BB = 0, tmp = 0;
  for (int l = 0; l < N; l++) {
    while (r < N && BB + B[r] * (r - l + 1) <= H) {
      tmp += A[r];
      BB += B[r] * (r - l + 1);
      r++;
    }
    ans = max(ans, tmp);
    if (l == r) r++;
    else {
      tmp -= A[l];
      BB -= sumB[r] - sumB[l];
    }
  }
  cout << ans << endl;
  return 0;
}