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# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;

class Program
{
	static void Main(string[] args)
	{
		var S = Console.ReadLine();
		var K = long.Parse(Console.ReadLine());
		var firstchr = S[0];
		int firstcount = 0;
		int lastcount = 0;
		int chgcount = 0;
		double ans;
		
		for (int i = 0; i < S.Length; i++) {
			if (S[i] == firstchr) {
				firstcount++;
			} else {
				break;
			}
		}
//		Console.WriteLine(string.Format("firstcount:{0}", firstcount));
		
		for (int i = S.Length - 1; i > 0; i--) {
			if (S[i] == firstchr) {
				lastcount++;
			} else {
				break;
			}
		}

//		Console.WriteLine(string.Format("lastcount:{0}", lastcount));
		
		for (int i = firstcount; i < S.Length - 1 - lastcount; i++) {
			if (S[i] == S[i + 1]) {
				chgcount++;
				i++;
			}
		}
		
		double firstcountblock = firstcount / 2;
		double lastcountblock = lastcount / 2;
		double chgcountblock = chgcount * K;
		double lastblocak = (firstcount + lastcount) / 2 * (K - 1);
//		Console.WriteLine(string.Format("firstcountblock:{0}", firstcountblock));
//		Console.WriteLine(string.Format("lastcountblock:{0}", lastcountblock));
//		Console.WriteLine(string.Format("chgcountblock:{0}", chgcountblock));
//		Console.WriteLine(string.Format("lastblocak:{0}", lastblocak));
		
		ans = firstcountblock + lastcountblock + chgcountblock+lastblocak;
		if (firstcount == S.Length){
			ans = K;
		}

		Console.WriteLine(ans);
		Console.ReadLine();
	}
}