/*
TASK:socks
LANG:C++
*/
#include<iostream.h>
#include<stdio.h>
#include<iomanip.h>
int main()
{int n,i,a[30],j,m,m2,m3,p,p2,p3;
long k;
double s[31],sum,d,sum2;
cin>>n>>k;
for(i=0;i<n;i++)cin>>a[i];
for(j=0;j<n+1;j++)cin>>s[j];
if(a[n-2]==a[0])m=a[n-1];else m=a[n-1]*(a[n-2]);
d=m*s[n];
p=k-m;
if(a[n-3]==a[0])m2=a[n-2];else m2=a[n-2]*a[n-3];
p2=k-m2;
sum2=s[n-1]+s[n-2];
sum=s[n]+s[n-1];
if(p2<=0 && sum2<sum)printf("%.2lf\n",sum2);else printf("%.2lf\n",sum);
return 0;}
