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: Accepted)

str = gets().split(" ");
q = str[0].to_i;
h = str[1].to_i;
s = str[2].to_i;
d = str[3].to_i;
n = gets().to_i;

q_p = q / 0.25;
h_p = h /0.5;
s_p = s / 1.0;
d_p = d / 2.0;

rank = Array.new(4);
rank[0] = q_p;
rank[1] = h_p;
rank[2] = s_p;
rank[3] = d_p;
rank.sort!


jun = Array.new(4);
for i in 0..3
	case rank[i]
	when q_p
		jun[i] = 1;
	when h_p
		jun[i] = 2;
	when s_p
		jun[i] = 4;
	when d_p
		jun[i] = 8;
	end
end

pay = 0;
n = n*4;

for j in 0..3
	count = 0
	count = n / jun[j];
	n = n % jun[j];
	case jun[j]
	when 1
		itibu = count*q;
	when 2
		itibu = count*h;
	when 4
		itibu = count*s;
	when 8
		itibu = count*d;
	end
		
	pay = pay + itibu;
end

puts(pay.to_i);