// #pragma GCC optimize("O3,unroll-loops")
#include <bits/stdc++.h>
// #include <x86intrin.h>
using namespace std;
#if __cplusplus >= 202002L
using namespace numbers;
#endif



int main(){
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(ios::badbit | ios::failbit);
	int n, th;
	cin >> n >> th;
	vector<int> a(n), b(n);
	copy_n(istream_iterator<int>(cin), n, a.begin());
	copy_n(istream_iterator<int>(cin), n, b.begin());
	vector<long long> prefa(n + 1), prefb(n + 1);
	for(auto i = 0; i < n; ++ i){
		prefa[i + 1] = prefa[i] + a[i];
		prefb[i + 1] = prefb[i] + b[i];
	}
	long long fat = 0, res = 0;
	for(auto l = 0, r = 0; l < n; ++ l){
		while(r < l || r < n && fat + 1LL * b[r] * (r + 1 - l) <= th){
			fat += 1LL * b[r] * (r + 1 - l);
			++ r;
		}
		res = max(res, prefa[r] - prefa[l]);
		fat -= prefb[r] - prefb[l];
	}
	cout << res << "\n";
	return 0;
}

/*

*/