#include <bits/stdc++.h>
using namespace std;
#define all(v) (v).begin(),(v).end()
#define pb(a) push_back(a)
#define rep(i, n) for(int i=0;i<n;i++)
#define foa(e, v) for(auto&& e : v)
using ll = long long;
const ll MOD7 = 1000000007, MOD998 = 998244353, INF = (1LL << 60);
#define dout(a) cout<<fixed<<setprecision(10)<<a<<endl;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n, h;
    cin >> n >> h;
    ll ans = 0;
    vector<ll> a(n), b(n);
    rep(i, n) cin >> a[i];
    rep(i, n) cin >> b[i];
    ll id = 0, sumansh = 0, sumans = 0, sumh = 0;
    for(int i = 0; i < n; i ++) {
        while(id < n and (id + 1 - i) * b[id] + sumansh <= h) {
            sumansh += b[id] * (id + 1 - i);
            sumh += b[id];
            sumans += a[id];
            id ++;
        } 
        ans = max(ans, sumans);
        sumansh -= sumh;
        sumh -= b[i];
        sumans -= a[i];
    }
    cout << ans << endl;
    return 0;
}