#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    ll H; cin >> 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];
    }
    ll res = 0;
    int r = 0;
    ll sum = 0, cost = 0, score = 0;
    for (int i = 0; i < n; ++i) {
        while (r < n and cost+b[r]*(r-i+1) <= H) {
            cost += b[r]*(r-i+1);
            sum += b[r];
            score += a[r];
            r += 1;
        }
        res = max(res, score);
        if (i == r) {
            r += 1;
        }
        else {
            cost -= sum;
            sum -= b[i];
            score -= a[i];
        }
    }
    cout << res << endl;
}