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: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strconv"
)

var scan *bufio.Scanner
var writer io.Writer

func init() {
	scan = bufio.NewScanner(os.Stdin)
	writer = os.Stdout
	scan.Split(bufio.ScanWords)
}

func main() {
	solve()
}

func solve() {
	var s string
	fmt.Scan(&s)
	var k int
	fmt.Scan(&k)

	res := 0
	c := 1
	cs := 1
	csf := true
	for i := 1; i < len(s); i++ {
		if s[i] == s[i-1] {
			c++
			if csf {
				cs++
			}
		} else {
			res += c / 2
			c = 1
			csf = false
		}
	}
	res += c / 2
	res = res * k
	if s[0] == s[len(s)-1] && c%2 == 1 && cs%2 == 1 {
		res += k - 1
	}
	fmt.Fprint(writer, res)
}

func nextWord() string {
	scan.Scan()
	str := scan.Text()
	return str
}

func nextInt() int {
	i, e := strconv.Atoi(nextWord())
	if e != nil {
		panic(e)
	}
	return i
}