using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    // static long[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, h) = (c[0], c[1]);
        var a = NList;
        var b = NList;
        var ans = 0L;
        var left = 0;
        var right = 0;
        var tire = 0L;
        var sat = 0L;
        var diffsum = 0L;
        while (true)
        {
            while (tire > h)
            {
                sat -= a[left];
                tire -= diffsum;
                diffsum -= b[left];
                ++left;
            }
            ans = Math.Max(ans, sat);
            if (right == n) break;
            sat += a[right];
            tire += (right - left + 1L) * b[right];
            diffsum += b[right];
            ++right;
            if (tire <= h) ans = Math.Max(ans, sat);
        }
        WriteLine(ans);
    }
}