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 Go (1.6) (judge verdict: Accepted)

package main

import "fmt"

func countPair(S string) (pair int) {
	for i := 0; i+1 < len(S); i++ {
		if S[i] == S[i+1] {
			pair++
			i++
		}
	}
	return pair
}

func main() {
	var s1, s2 string
	var k, ans int
	fmt.Scan(&s1, &k)
	m := make(map[byte]int, 0)
	for i := 0; i < len(s1); i++ {
		m[s1[i]]++
	}
	p1 := countPair(s1)
	s2 = s1 + s1
	p2 := countPair(s2)
	if len(m) == 1 {
		ans = len(s1) * k / 2
	} else if p1*2 == p2 {
		ans = p1 * k
	} else {
		d := p2 - p1*2
		ans = p1*k + (k-1)*d
	}
	fmt.Println(ans)
}