#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	long long h; cin >> h;
	vector<long long>a(n), b(n), sb(n + 1);
	rep(i, n)cin >> a[i];
	rep(i, n)cin >> b[i];
	rep(i, n)sb[i + 1] = sb[i] + b[i];
	long long ans = 0;
	long long tmp = 0;
	long long hp = 0;
	int r = 0;
	for (int l = 0; l < n; ++l) {
		while (r < n && hp + b[r] * (r - l + 1) <= h) {
			tmp += a[r];
			hp += b[r] * (r - l + 1);
			r++;
		}
		chmax(ans, tmp);
		if (l == r)r++;
		else {
			tmp -= a[l];
			hp -= sb[r] - sb[l];
		}
	}
	cout << ans << endl;
	return 0;
}