
list1 = [int(i) for i in input().split(' ')]
list2 = [int(i) for i in input().split(' ')]
n = list1[0]
w = list1[1] #水量
listman = list2[:n]
listwoman = list2[n:]
man = min(listman)/2.0
woman = min(listwoman)
m = min(man, woman)
x = m * n * 3
m = min(x, w)
print(round(m, 6))

import java.util.Scanner;
public class Test2 {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
String str=sc.nextLine();
String num[]=str.split(" ");
int n=Integer.parseInt(num[0]);
int a=Integer.parseInt(num[1]);
int b=Integer.parseInt(num[2]);
int c=Integer.parseInt(num[3]);
int sum=0;
if (n>=c&&c!=0){
int i=n/c;
sum+=i;
if(i>=a){
sum+=b;
}
}
System.out.println(sum);
}
}
