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>
#include <malloc.h>

int main() {
    char *str = NULL;
    unsigned long long K = 0;
    scanf("%m[^\n]%Lu", &str, &K);
    int stringLength = strlen(str);
    int i = 1;
    unsigned long long sum = 0;
    while (i < 2 * stringLength) {
        if (i != (2 * stringLength - 1) && str[i % stringLength] == str[(i - 1) % stringLength] && str[i % stringLength] == str[(i + 1) % stringLength]) {
            sum++;
            i += 2;
        } else if (i != (2 * stringLength - 1) && str[i % stringLength] == str[(i + 1) % stringLength]) {
            i++;
        } else if (str[i % stringLength] == str[(i - 1) % stringLength]) {
            i += 2;
            sum++;
        } else {
            i += 2;
        }
    }

    if (sum % 2 == 1) {
        printf("%Lu", (K - 1) * (sum / 2 + 1) + sum / 2);
    } else {
        printf("%Lu", K * sum / 2);
    }
    free(str);
    str = NULL;
    return 0;
}