Problem:
Score : 300 points

Problem Statement

You've come to your favorite store Infinitesco to buy some ice tea.

The store sells ice tea in bottles of different volumes at different costs.
Specifically, a 0.25-liter bottle costs Q yen, a 0.5-liter bottle costs H yen, a 1-liter bottle costs S yen, and a 2-liter bottle costs D yen.
The store has an infinite supply of bottles of each type.

You want to buy exactly N liters of ice tea. How many yen do you have to spend?

Constraints

1 \leq Q, H, S, D \leq 10^8

1 \leq N \leq 10^9

All input values are integers.

Input

Input is given from Standard Input in the following format:

Q H S D
N

Output

Print the smallest number of yen you have to spend to buy exactly N liters of ice tea.

Sample Input 1

20 30 70 90
3

Sample Output 1

150

Buy one 2-liter bottle and two 0.5-liter bottles. You'll get 3 liters for 90 + 30 + 30 = 150 yen.

Sample Input 2

10000 1000 100 10
1

Sample Output 2

100

Even though a 2-liter bottle costs just 10 yen, you need only 1 liter.
Thus, you have to buy a 1-liter bottle for 100 yen.

Sample Input 3

10 100 1000 10000
1

Sample Output 3

40

Now it's better to buy four 0.25-liter bottles for 10 + 10 + 10 + 10 = 40 yen.

Sample Input 4

12345678 87654321 12345678 87654321
123456789

Sample Output 4

1524157763907942

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

include Math

if __FILE__==$0
	inf=Float::INFINITY
	
	readln_i=lambda{|dl|gets.chomp.split(dl).map(&:to_i)}
	read_i=lambda{gets.chomp.to_i}
	readln_s=lambda{|dl|fp.gets.chomp.split(dl)}
	read_s=lambda{fp.gets.chomp}
	
	q,h,s,d=readln_i[" "]
	n=read_i[]
	
	cs=[[q*4,1],[h*2,1],[s,1],[d/2,2]]
	cs.sort! do |a,b|
		a[0]<=>b[0]
	end
	
	ans=0
	if cs[0][1]==2
		x=n/2
		ans+=x*(cs[0][0]*2)
		n-=x*2
		if n>0
			x=n
			ans+=x*cs[1][0]
		end
	else
		ans+=n*cs[0][0]
	end
	p ans
end