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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

fun main(args: Array<String>) {
  val s = readLine()!!.toList()
  val k = readLine()!!.toInt()

  val s1 = s.toMutableList()
  var cnt1 = 0L
  for (i in 1 until s.size) {
    val a = s1[i - 1]
    val b = s1[i]
    if (a == b) {
      s1[i] = '_'
      cnt1++
    }
  }

  if (k == 1) {
    println(cnt1)
    return
  }
  if (s1.first() != s1.last()) {
    println(cnt1 * k)
    return
  }

  val s2 = s.toMutableList()
  s2[0] = '_'
  var cnt2 = 1L
  for (i in 1 until s.size) {
    val a = s2[i - 1]
    val b = s2[i]
    if (a == b) {
      s2[i] = '_'
      cnt2++
    }
  }

  if (s1.first() != s2.last()) {
    println((cnt1 + cnt2) * k / 2 + cnt1 * k % 2)
  } else {
    println(cnt1 + cnt2 * (k - 1))
  }
}