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: Wrong Answer)

def sum(s,k)
  if s.split('').all?{|c| c==s[0] }
    puts s.length*k/2
  else
    top=0
    s.each_char.with_index do |c,i|
      next if i == 0
      if c==s[i-1]
        top+=1
      else
        next
      end
    end
    bot=0
    rs=s.reverse
    s.each_char.with_index do |c,i|
      next if i == 0
      if c==rs[i-1]
        bot+=1
      else
        next
      end
    end
    cnt=0
    s.each_char.with_index do |c,i|
      next if i ==0
      if c == s[i-1]
        s[i]='0'
        cnt+=1
      end
    end
    all=cnt*k
    if s[0] == s[s.length-1]
      all+=(top+bot)/2 * (k-1)+ top/2+(bot/2)
      puts all
    else
      #all+=((top/2+(bot/2))*k)
      puts all
    end
  end
end

sum(gets.chomp, gets.chomp.to_i)