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: Wrong Answer)

<?php
# get a integer
fscanf(STDIN, "%s", $s);
# get two integers separated with half-width break
fscanf(STDIN, "%d", $k);

$parts = [];
$n = strlen($s);

$part = '';
$new = true;
for ($i=0; $i < $n ; $i++) { 
	if($i==0){
		$part = $s[$i];
	}else{
		if($s[$i]==$s[$i-1]){
			$part .= $s[$i];
		}else{
			$parts[] = $part;	
			$part = $s[$i]; 
		}
	}
}
if($part !='')
	$parts[] = $part;

$ans = 0;

$p = count($parts);


if($p>1)
{
	if($s[0]!=$s[$n-1]){
		foreach ($parts as $i => $part) {
			$ans += $k*onePiece($part);
		}

	}else{
		foreach ($parts as $i => $part) {
			if($i!=0 && $i!=$p-1){
				$ans += $k*onePiece($part);
			}
		}
		$ss = $parts[$p-1].$parts[0];
		$ans += onePiece($ss,$k-1);

		$ans+=onePiece($parts[0]);
		$ans+=onePiece($parts[$p-1]);

	}
}else{
	$ans = onePiece($parts[0],$k);
	//$ans += strlen($parts[0])==1?($k-1):($k*(intval((strlen($parts[0])+1)/2)));
}

function onePiece($s,$k=1){
	$n = strlen($s)*$k;
	
	$ans =0 ;
	switch ($n) {
		case 0:
		case 1:
			$ans = 0;
		break;
		default:
			$ans = intval($n/2);
	}
	return  $ans;
}

# output
echo $ans;