#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, n) for(int i = a; i < n; i++)
#define rrep(i, a, n) for(int i = a; i >= n; i--)
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
// constexpr ll MOD = 1000000007;
constexpr ll MOD = 998244353;
constexpr int IINF = 1001001001;
constexpr ll INF = 1LL<<60;

template<class t,class u> void chmax(t&a,u b){if(a<b)a=b;}
template<class t,class u> void chmin(t&a,u b){if(b<a)a=b;}

int main(){
    ll n, h; cin >> n >> h;
    vector<ll> a(n), b(n);
    rep(i, 0, n) cin >> a[i];
    rep(i, 0, n) cin >> b[i];
    vector<ll> acc(n+1);
    rep(i, 0, n) acc[i+1] = acc[i]+a[i];
    vector<ll> acc_b(n+1);
    rep(i, 0, n) acc_b[i+1] = acc_b[i]+b[i];
    vector<ll> fatigue(n+1);
    rep(i, 0, n) fatigue[i+1] = fatigue[i]+b[i]*(i+1);

    ll ok = 0, ng = 1e18;
    while(ng-ok > 1){
        ll mid = (ok+ng)/2;
        bool f = false;
        rep(i, 0, n){
            auto itr = lower_bound(acc.begin(), acc.end(), mid+acc[i]);
            if(itr == acc.end()) continue;
            ll l = i, r = itr-acc.begin();
            if(h >= (fatigue[r]-fatigue[l])-(acc_b[r]-acc_b[l])*l) f = true;
        }
        if(f) ok = mid;
        else ng = mid;
    }
    cout << ok << endl;
    return 0;
}