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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <string.h>

int main()
{
    char s[100];
    int i;
    long long k,ans = 0;

    scanf("%s %lld",s,&k);

    int len = strlen(s);
    int cnt = 0,a = 0,b = 0;

    for (i = 1; i < len; i++)
    {
        if(s[i - 1] != s[i])break;
    }
    a = i;
    if(i == len)
    {
        printf("%lld",k * len / 2);
    }
    else
    {
        for (i = 1; i < len; i++)
        {
            if(s[i - 1] == s[i])cnt++;
            else
            {
                ans += cnt / 2;
                cnt = 0;
            }
        }
        ans += cnt / 2;

        if(s[0] == s[len - 1])
        {
            for (i = len; i > 0 ;i--)
            {
                if(s[i - 1] != s[i])break;
            }
            b = len - i;
            printf("%lld",k * ans - (((a / 2 + b / 2) - (a + b) / 2)) * (k - 1));
        }
        else
        {
            printf("%lld",k * ans);
        }
        
    }
    
}