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.Diagnostics;
using System.IO;

class _Class
{
	void _Do()
	{
		//
		var a_ = _longArray();
		var N_ = _longArray();
		
		//
		long _l = Math.Min(a_[0]*4, a_[1]*2);
		_l = Math.Min(_l, a_[2]);

		long _2l = a_[3];

		long _リットル = N_[0];

		//
		{
			// 2l
			if (_リットル % 2 == 0)
			{
				// guusuu
				var yasui2l = Math.Min(_l*2,_2l);
				Console.WriteLine(yasui2l * _リットル /2);
			}
			else
			{
				// kisuu
				if (_2l>_l*2) {
					//
					Console.WriteLine(_リットル*_l);
				} else {
					//
					long ダブル = _リットル / 2;
					Console.WriteLine(ダブル*_2l　+　1*_l);
				}
			}
		}

	}	

	static void Main(string[] args)
	{
		new _Class()._Do();
	}


	// 1
	string[] _stringArray()
	{
		return Console.ReadLine().Split();
	}

	// 2.1 -2,147,483,648 ~ +2,147,483,647
	int[] _intArray()
	{
		var _s = Console.ReadLine().Split();

		var x = new int[_s.Length];
		for (var i = 0; i < _s.Length; i++)
			x[i] = int.Parse(_s[i]);

		return x;
	}

	// 2.2 -9,223,372,036,854,775,808 ~ +9,223,372,036,854,775,807
	long[] _longArray()
	{
		var _s = Console.ReadLine().Split();

		var x = new long[_s.Length];
		for (var i = 0; i < _s.Length; i++)
			x[i] = long.Parse(_s[i]);

		return x;
	}
}