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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder.Abc
{
    public class QuestionA
    {
        public static void Main(string[] args)
        {
            // 整数配列の入力
            var inputLongArray = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();

            Dictionary<double, long> prices = new Dictionary<double, long>();
            prices.Add(0.25, inputLongArray[0]);
            prices.Add(0.5, inputLongArray[1]);
            prices.Add(1.0, inputLongArray[2]);
            prices.Add(2.0, inputLongArray[3]);

            Dictionary<double, long> tanka = new Dictionary<double, long>();
            tanka.Add(0.25, inputLongArray[0] * 4);
            tanka.Add(0.5, inputLongArray[1] * 2);
            tanka.Add(1.0, inputLongArray[2]);
            tanka.Add(2.0, inputLongArray[3] / 2);
            var sort = tanka.OrderBy(x => x.Value);

            Dictionary<double, long> lowPrices = new Dictionary<double, long>();
            foreach(var item in sort) {
                lowPrices.Add(item.Key, prices[item.Key]);
            }

            // 整数の入力
            double n = long.Parse(Console.ReadLine());

            long money = 0;
            foreach (var price in lowPrices) {
                while(n >= price.Key) {
                    money += price.Value;
                    n -= price.Key;
                }
            }
            Console.WriteLine(money);

        }
    }
}