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);

            //// 文字列の入力
            //string s = Console.ReadLine();

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

            //// 文字列配列の入力
            //string[] inputStrArray = Console.ReadLine().Split(' ');

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

            var inputLongArray = Console.ReadLine().Split(' ').Select(i => long.Parse(i)).ToArray();
            long n = long.Parse(Console.ReadLine());

            var volume = n;

            var Q = inputLongArray[0];
            var H = inputLongArray[1];
            var S = inputLongArray[2];
            var D = inputLongArray[3];

            var ones = new List<long>();

            ones.Add(S);
            ones.Add(H * 2);
            ones.Add(H + Q * 2);
            ones.Add(Q * 4);

            var one = ones.Min();

            var twos = new List<long>();

            twos.Add(D);
            twos.Add(S * 2);
            twos.Add(S + H * 2);
            twos.Add(S + H + Q * 2);
            twos.Add(S + Q * 4);
            twos.Add(H * 4);
            twos.Add(H * 3 + Q * 2);
            twos.Add(H * 2 + Q * 4);
            twos.Add(H * 1 + Q * 6);
            twos.Add(Q * 8);

            var two = twos.Min();

            long result = 0;

            if (n % 2 == 0) {
                var nn = n / 2;
                result = nn * two;
            } else {
                var nn = n / 2;
                result = nn * two + one;
            }

            Console.WriteLine(result.ToString());

            Console.Out.Flush();
        }
    }
}