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;

namespace AtCoder.Abc
{
    class QuestionC
    {
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            // 整数配列の入力
            var inputLongArray = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();

            // 整数の入力
            long n = long.Parse(Console.ReadLine()) * 100;

            var capacity = new int[] {
                25, 50, 100, 200
            };

            var q = inputLongArray[0];
            var h = inputLongArray[1];
            var s = inputLongArray[2];
            var d = inputLongArray[3];

            var qq = inputLongArray[0];
            var hh = inputLongArray[1] / 2.0;
            var ss = inputLongArray[2] / 4.0;
            var dd = inputLongArray[3] / 8.0;

            var list = new List<double> {
                qq, hh, ss, dd
            };

            var min0 = list.LastIndexOf(list.Min());
            list[min0] = double.MaxValue;
            var min1 = list.LastIndexOf(list.Min());
            list[min1] = double.MaxValue;
            var min2 = list.LastIndexOf(list.Min());
            list[min2] = double.MaxValue;
            var min3 = list.LastIndexOf(list.Min());
            list[min3] = double.MaxValue;

            var a = n / capacity[min0];
            n -= a * capacity[min0];

            var b = n / capacity[min1];
            n -= b * capacity[min1];

            var c = n / capacity[min2];
            n -= c * capacity[min2];

            var e = n / capacity[min3];
            n -= e * capacity[min3];

            var val = a * inputLongArray[min0];
            val += b * inputLongArray[min1];
            val += c * inputLongArray[min2];
            val += e * inputLongArray[min3];

            Console.WriteLine(val);

            Console.Out.Flush();
        }
    }
}