Problem:
Score : 300 points

Problem Statement

Given is a string S. Let T be the concatenation of K copies of S.
We can repeatedly perform the following operation: choose a character in T and replace it with a different character.
Find the minimum number of operations required to satisfy the following condition: any two adjacent characters in T are different.

Constraints

1 \leq |S| \leq 100

S consists of lowercase English letters.

1 \leq K \leq 10^9

K is an integer.

Input

Input is given from Standard Input in the following format:

S
K

Output

Print the minimum number of operations required.

Sample Input 1

issii
2

Sample Output 1

4

T is issiiissii. For example, we can rewrite it into ispiqisyhi, and now any two adjacent characters are different.

Sample Input 2

qq
81

Sample Output 2

81

Sample Input 3

cooooooooonteeeeeeeeeest
999993333

Sample Output 3

8999939997

Solution in PHP7 (7.0.15) (judge verdict: Runtime Error)

<?php

$string = fgets(STDIN);
$repeat_count = fgets(STDIN);

$arr = [];
$count = 0;
for ($i = 0; $i < mb_strlen($string) - 1; $i++) {
    $current_char = $string[$i];
    $next_char = $string[$i + 1];

    if ($current_char === $next_char) {
        $arr[$current_char] += 1;
    } else {
        $count += floor(($arr[$current_char] + 1) / 2);
        $arr[$current_char] = 0;
    }
}

$first_char = $string[0];
$last_char = $string[mb_strlen($string) - 1];

echo $last_char . PHP_EOL;

// 全部同じ文字
if (count($arr) === 1) {
    $count += floor(($arr[$first_char] + 1) / 2);
} else if ($first_char === $last_char) {
    $count += 1;
}

echo $count * $repeat_count;