import java.util.ArrayList;
import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        ArrayList<String> arr1 = new ArrayList<>();
        ArrayList<String> arr2 = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        int count = 0;

        while (true)
        {
            String str = scanner.nextLine();
            if (!str.equals( "EOF"))
            {
                if (str.equals("<") ||str.isEmpty())
                    continue;
                arr1.add(exam(str));
            }
            else
                break;
        }

        while (true)
        {
            String str2 = scanner.nextLine();
            if (!str2.equals("EOF"))
            {
                if (str2.equals("<") || str2.isEmpty())
                    continue;
                arr2.add(exam(str2));
            }
            else
                break;
        }

        int time = scanner.nextInt();

        for (int i = 0; i < Math.min(arr1.size(), arr2.size()); i++)
            for (int i2 = 0; i2 < Math.min(arr1.get(i).length(), arr2.get(i).length()); i2++)
                if (arr1.get(i).charAt(i2) == arr2.get(i).charAt(i2))
                    count++;

        System.out.println(r(count, time));
    }

    public static String exam (String str)
    {
        StringBuilder a = new StringBuilder(str);

        if (a.charAt(0) == '<')
            a.delete(0, 1);

        for (int i = 0; i < a.length(); i++)
        {
            if (a.charAt(i) == '<' && i > 0)
                a.delete(i - 1, i + 1);
        }

        return a.toString();
    }

    public static long  r (int count, int time)
    {
        double a = count;
        double b = time;
        double c = 60.0;
        return Math.round(a / b * c);
    }
}