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 Ruby (2.3.3) (judge verdict: Accepted)

def count_cont(s)
    bef = ''
    cnt = 0
    s.each_char do |c|
        if c == bef
            cnt += 1
            bef = 'Z'
        else
            bef = c
        end
    end
    #puts cnt
    cnt
end

def aa
    s = gets.chomp
    k = gets.chomp.to_i

    if s.length == 1
        puts (k/2.0).floor
        exit
    end

    if s.split("").uniq.length == 1
        if s.length%2 == 0
            puts s.length/2 * k
        else
            if k == 1
                puts s.length/2
            elsif k%2 == 0
                puts k/2 * s.length
            else
                puts k/2 * s.length + s.length/2
            end
        end
        exit
    end

    cnt1 = count_cont(s)
    if k == 1
        puts cnt1
    elsif k%2 == 0
        cnt2 = count_cont(s+s)
        puts (k-1)*(cnt2-cnt1) + cnt1
    else
        cnt2 = count_cont(s+s)
        puts (k-1)*(cnt2-cnt1) + cnt1
    end
end

aa