#include <bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n, h;
    cin >> n >> h;
    vector<ll> a(n), b(n), as(n + 1), bs(n + 1), cs(n + 1);
    cin >> a >> b;
    for(int i = 0; i < n; i++){
        as[i + 1] = as[i] + a[i];
        bs[i + 1] = bs[i] + b[i];
        cs[i + 1] = cs[i] + (i + 1) * b[i];
    }
    ll ans = 0;

    for(int i = 0; i < n; i++){
        ll ok = i, ng = n + 1, mid;
        while(ok + 1 < ng) {
            mid = (ok + ng) / 2;
            ll S1 = bs[mid] - bs[i];
            ll S2 = cs[mid] - cs[i];
            (S2 - S1 * i <= h ? ok : ng) = mid;
        }
        ans = max(ans, as[ok] - as[i]);
    }

    cout << ans << '\n';
}