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;
using System.Text;
using System.Threading.Tasks;

using static System.Console;
namespace AtCoder.AGC019
{
    class IceTeaStore
    {
        public static void Main()
        {
            var sizes = new Decimal[] { 0.25M, 0.5M, 1, 2 };
            var price = ReadLine().Trim().Split(' ').Select((p,idx) => new IceTea(int.Parse(p), sizes[idx])).OrderBy(_ => _.Tanka);
            var demand = Decimal.Parse(ReadLine().Trim());
            decimal res = 0;
            while (demand != 0) {
                foreach(var p in price) {
                    if (demand == 0) break;
                    var count = Math.Floor(demand / p.Size);
                    res += count * p.Price;
                    demand -= count * p.Size;
                }
            }
            WriteLine(res);
        }
        struct IceTea
        {
            public IceTea(int p, Decimal s)
            {
                Price = p; Size = s;
            }
            public int Price { get; private set; }
            public Decimal Size { get; private set; }
            public Decimal Tanka
            {
                get { return Price / Size; }
            }
        }
    }
}