#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;

ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const dynamic_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

template<typename T> void chmin(T& a, T b){a = min(a, b);}
template<typename T> void chmax(T& a, T b){a = max(a, b);}

int main(){
	int n;
	long long h;
	cin >> n >> h;
	vector<long long> a(n);
	vector<long long> b(n);
	cin >> a >> b;
	vector<long long> b_cum(n + 1);
	rep(i, n) b_cum[i + 1] = b_cum[i] + b[i];
	int l = 0, r = 0;
	long long satisfy = 0;
	long long fatigue = 0;
	long long ans = 0;
	auto left = [&]{
		satisfy -= a[l];
		fatigue -= b_cum[r] - b_cum[l];
		l++;
		if(fatigue <= h) chmax(ans, satisfy);
	};
	auto right = [&]{
		satisfy += a[r];
		fatigue += (r - l + 1) * b[r];
		r++;
		if(fatigue <= h) chmax(ans, satisfy);
	};
	while(true){
//		cout << l << ' ' << r << ' ' << satisfy << ' ' << fatigue << "\n";
		if(fatigue<= h and r < n){
			right();
		}else{
			left();
			if(l == n) break;
		}
	}
	cout << ans << "\n";
	return 0;
}