#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    long long N,H; cin >> N >> H;
    vector<long long> A(N),B(N);
    for(auto &a : A) cin >> a;
    for(auto &b : B) cin >> b;

    long long answer = 0,nowa = 0,nowb = 0,pos = 0,sumb = 0;
    for(int i=0; i<N; i++){
        while(pos != N){
            long long a = A.at(pos),b = B.at(pos);
            long long nb = nowb+(pos-i+1)*b;
            if(nb > H) break;
            pos++; nowb = nb;
            nowa += a; sumb += b;
        }
        answer = max(answer,nowa);
        if(pos == i) pos++;
        else{
            nowa -= A.at(i); nowb -= sumb;
            sumb -= B.at(i);
        }
    }
    cout << answer << endl;
}