import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

/*
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/**
 *
 * @author cteam024
 */
public class Barrels
{
    static String a = "";
    static String list[];
    static int count = 0;
    static int found = 0;
    static char[] digits = new char[3];
    static int k;
    public static void main(String[] args) throws Exception
    {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] input = reader.readLine().split(" ");
        k = Integer.parseInt(input[2]);
        digits[0] = input[0].charAt(0);
        digits[1] = input[1].charAt(0);
        digits[2] = input[3].charAt(0);
        int identical = 0;
        if (digits[0] == digits[1]) identical++;
        if (digits[1] == digits[2]) identical++;
        if (digits[0] == digits[2] && identical < 2) identical++;
        list = new String[(int)Math.pow(3 - identical, k)];
        combination(0);
        System.out.println(count % 1000000007);
        System.exit(0);
    }
    
    static boolean contains(String a)
    {
        for (int i = 0; i < found; i++)
        {
            if (list[i].equals(a))
            {
                return true;
            }
        }
        return false;
    }
    
    static int cInString(String a, char c)
    {
        int num = 0;
        for (int i = 0; i < a.length(); i++) {
            if (a.charAt(i) == c)
            {
                num++;
            }
        }
        return num;
    }
    
    static void comb(int k, char[] digits)
    {
        String str = "";
        for (int i = 0; i < digits.length; i++)
        {
            for (int j = i; j < k; j++)
            {
                str += digits[i];
            }
        }
    }
    
    static void combination(int index)
    {
        if (index >= k)
        {
            if (!contains(a))
            {
                list[found] = a;
                count += cInString(a, digits[2]);
                found++;
                //System.out.println(a);
            }
            a = a.substring(0, a.length() - 1);
            return;
        }
        for (int i = 0; i < digits.length; i++)
        {
            a += digits[i];
            combination(index + 1);
        }
        if (a.length() > 0)
            a = a.substring(0, a.length() - 1);
    }
}