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>
typedef long long ll;
int main() {
	char s[101];
	int k;
	scanf("%s%d", s, &k);
	int n = strlen(s), cnt = 1;
	ll ans = 0;
	for (int i = 0; i < n; i++) {
		if (i != n - 1 && s[i] == s[i + 1]) {
			cnt++;
		} else {
			ans += cnt / 2;
			cnt = 1;
		}
	}
	ans = ans * k;
	if (s[0] == s[n - 1]) {
		int t = 1, h = 1;
		while (s[t] == s[0]) {
			t++;
			if (t == n) {
				printf("%lld\n", n * k / 2);
				return 0;
			}
		}
		while (s[n - h - 1] == s[n - 1]) {
			h++;
		}
		ans -= ((ll)(t / 2 + h / 2 - (t + h) / 2) * (k - 1));
	}
	printf("%lld\n", ans);
	return 0;
}