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 Java7 (OpenJDK 1.7.0) (judge verdict: Accepted)

import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.Scanner;
import java.math.BigInteger;

public class Main
{
	static long min(long a,long b) {
		if(a<b) {
			return a;
		}
		else {
			return b;
		}
	}
	public static void main (String[] args) throws java.lang.Exception
	{
		
		Scanner cin = new Scanner(System.in);
		long q,h,f,s;
		q = cin.nextLong();
		h = cin.nextLong();
		f = cin.nextLong();
		s = cin.nextLong();
		long n = cin.nextLong();
		long v1 = min(min(q*4,h*2),f);
		if(n%2==0) {
			System.out.println(min(n*v1,s*(n/2)));
		}
		else {
			System.out.println(min(n*v1,(s*(n/2))+v1));
		}
	}
}