import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class Main {
    static int times, cnt;
    static StringBuilder tmp;
    static List<StringBuilder> l1 = new ArrayList<>();
    static List<StringBuilder> l2 = new ArrayList<>();
    public static void main(String[] args) throws IOException {
        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));

        tmp = new StringBuilder(bf.readLine());
        while(!tmp.toString().equals("EOF")) {
            pro_del();
            if(!tmp.isEmpty()) l1.add(tmp);;
            tmp = new StringBuilder(bf.readLine());
        }
        tmp = new StringBuilder(bf.readLine());
        while(!tmp.toString().equals("EOF")) {
            pro_del();
            if(!tmp.isEmpty()) l2.add(tmp);
            tmp = new StringBuilder(bf.readLine());
        }
        times = Integer.parseInt(bf.readLine());

        for (int i = 0; i < l1.size() && i < l2.size(); i++) {
            StringBuilder s1 = l1.get(i); StringBuilder s2 = l2.get(i);
            for(int j = 0; j < s1.length() && j < s2.length(); j++) {
                if(s1.charAt(j) == s2.charAt(j)) cnt++;
            }
        }
        pw.println((cnt * 60 / times));
        pw.flush();
    }

    public static void pro_del() {
        int i = 0;
        while(i < tmp.length()) {
            if(tmp.charAt(i) != '<') {
                i++;
                continue;
            }
            if(i == 0) tmp.deleteCharAt(i);
            else{
                tmp.deleteCharAt(i - 1);
                tmp.deleteCharAt(i - 1);
                i--;
            }
        }
    }
}