#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <cstdlib>
#include <map>
#include <unordered_map>
#include <queue>
#include <vector>
#include <list>
#include <algorithm>
#include <cmath>
#include <set>
#include <unordered_set>
#include <numeric>

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
#define REP(i,n) for(int (i) = 0; (i) < (n); ++(i))
#define FOR(i,a,b) for(int (i) = a; (i) < (b); ++(i))

int a[200010];
int b[200010];

int main ()
{
    int n, h;
    cin >> n >> h;
    REP(i,n) cin >> a[i];
    REP(i,n) cin >> b[i];
    int j = 0;
    ll hard = 0;
    ll best = 0;
    ll ans = 0;
    ll sum = 0;
    REP(i,n) {
        if (j < i) {
            j = i;
            hard = 0;
            best = 0;
            sum = 0;
        }
        while (j < n) {
            ll nxt = ll(j-i+1) * b[j];
            if (hard + nxt <= h) {
                hard += nxt;
                best += a[j];
                sum += b[j];
                ++j;
            } else break;
        }
        if (j > i) {
            ans = max(ans, best);
            sum -= b[i];
            hard -= b[i];
            hard -= sum;
            best -= a[i];
        }
    }
    cout << ans << endl;
}