#include <bits/stdc++.h>

#define ll long long
#define int ll
#define pii pair<int, int>
#define all(a) (a).begin(), a.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define pb push_back
#define files(in, out) freopen(in, "r", stdin); freopen(out, "w", stdout)
#define ff first
#define ss second

using namespace std;

int sum(vector<int> &pref, int l, int r){
    if (l == 0) return pref[r];
    return pref[r] - pref[l - 1];
}

void solve(){
    int n, s;
    cin >> n >> s;
    vector<int> t(n), cost(n);
    vector<int> pref(n), pref_cost(n);
    rep(i, n){
        cin >> t[i];
        if (i == 0) pref[i] = t[i];
        else pref[i] = pref[i - 1] + t[i];
    }
    rep(i, n){
        cin >> cost[i];
        if (i == 0) pref_cost[i] = cost[i] * t[i];
        else pref_cost[i] = pref_cost[i - 1] + cost[i] * t[i];
    }
    int ans = 0;
    int time = 0;
    for (int i = 0; i < n; ++i){
        int l = i;
        int r = n;
        while (r - l > 1){
            int mid = (l + r) / 2;
            if (sum(pref, i, mid) <= s){
                l = mid;
            }
            else{
                r = mid;
            }
        }
        int plus = s - sum(pref, i, l);
        int mb_ans = sum(pref_cost, i, l);
        vector<pii> mbo;
        if (i > 0) mbo.pb({cost[i - 1], i - 1});
        if (l < n - 1) mbo.pb({cost[l + 1], l + 1});
        sort(all(mbo));
        reverse(all(mbo));
        for (auto el : mbo){
            int plus_time = min(plus, t[el.ss]);
            mb_ans += plus_time * cost[el.ss];
            plus -= plus_time;
        }
        ans = max(ans, mb_ans);
    }
    cout << ans;
}

signed main() {
    //files("moscow.in", "moscow.out");
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    //cin >> t;
    while (t--) solve();
    return 0;
}