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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
	static void Main()
	{
		long[] t = Array.ConvertAll(Console.ReadLine().Split(new[] { ' ' }), number => long.Parse(number));
		long n = long.Parse(Console.ReadLine());

		var datas = new[] {
			new {
				Ryo = 250,
				Cost = t[0],
				Perf = t[0] * 8,
			},
			new {
				Ryo = 500,
				Cost = t[1],
				Perf = t[1] * 4,
			},
			new {
				Ryo = 1000,
				Cost = t[2],
				Perf = t[2] * 2,
			},
			new {
				Ryo = 2000,
				Cost = t[3],
				Perf = t[3],
			},
		};

		Array.Sort(datas, (d1, d2) => d1.Perf < d2.Perf ? -1 : 1);

		long total = 0;
		long last = n * 1000;
		foreach (var data in datas) {
			if (last >= data.Ryo) {
				long ans = last / data.Ryo;
				total += ans * data.Cost;
				last = last % (ans * data.Ryo);
			}
		}

		Console.WriteLine(total);

		//デバッグ実行での確認用。そのまま提出しても問題なし
		Console.ReadKey();
	}
}