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 PHP (5.6.30) (judge verdict: Wrong Answer)

<?php

// define('DEBUG', true);
define('DEBUG', false);

$target = "a";

fscanf(STDIN, "%d %d %d %d", $Q, $H, $S, $D);
fscanf(STDIN, "%d", $N);

$litter = min($Q * 4, $H * 2, $S);

// echo "{$litter} {$D} {$N}\n";

if ($litter * 2 < $D) {
    $ans = $N * $litter;
} else {
    // echo "BINGO\n";
    $num = floor($N / 2);
    $mod = $N % 2;
    $ans = $num * $D + $mod * $litter;
    // echo "{$num} * {$D} + {$mod} * {$litter}\n";
}

// echo $ans . PHP_EOL;

printf ("%d\n", 
        (floor($N / 2) * min(8 * $Q, 4 * $H, 2 * $S, $D)) +
        (($N % 2) * min(4 * $Q, 2 * $H, $S))
    );