#include <iostream>
#include <vector>
#include <algorithm>
#include <array>
#include <iterator>
#include <string>
#include <cctype>
#include <cstring>
#include <cstdlib>
#include <cassert>
#include <cmath>
#include <ctime>
#include <iomanip>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <bitset>
#include <random>
#include <utility>
#include <functional>
using namespace std;
void Main()
{
	int N,H;
	cin >> N >> H;
	vector<int> A(N),B(N);
	for(int i = 0;i < N;i++)
	{
		cin >> A[i];
	}
	for(int i = 0;i < N;i++)
	{
		cin >> B[i];
	}
	vector<long long> SA(N + 1);
	vector<long long> SB(N + 1);
	for(int i = 0;i < N;i++)
	{
		SA[i + 1] = SA[i] + A[i];
		SB[i + 1] = SB[i] + B[i];
	}
	using i128 = __int128_t;
	vector<i128> SSB(N + 1);
	for(int i = 0;i < N;i++)
	{
		SSB[i + 1] = SSB[i] + (long long) (i + 1) * B[i];
	}
	long long ans = 0;
	for(int i = 0;i < N;i++)
	{
		int ok = i,ng = N + 1;
		while(ng - ok > 1)
		{
			int mid = (ok + ng) / 2;
			i128 cur = 0;
			cur += SSB[mid] - SSB[i];
			cur -= (i128) (SB[mid] - SB[i]) * i;
			if(cur <= H)
			{
				ok = mid;
			}
			else
			{
				ng = mid;
			}
		}
		ans = max(ans,SA[ok] - SA[i]);
	}
	cout << ans << "\n";
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int tt = 1;
	/* cin >> tt; */
	while(tt--) Main();
}