#include<bits/stdc++.h>
using namespace std;
using ll=long long;
int main(){
  ll n,h,a=0,b=0,ans=0,j=1;cin>>n>>h;vector<ll> A(n+1,0),B(n+1,0),C(n+1,0);
  for(int i=1;i<=n;i++)cin>>A[i];
  for(int i=1;i<=n;i++){cin>>B[i];C[i]=B[i]+C[i-1];}
  for(int i=1;i<=n;i++){
    a+=A[i];
    b+=B[i]*(i-j+1);
    while(b>h&&j<=i){b-=(C[i]-C[j-1]);a-=A[j];j++;}
    ans=max(ans,a);
  }
  cout<<ans;
}