package a_examPreparation1;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class GoogleSearches {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        int days = Integer.parseInt(reader.readLine());
        int usersCountPerDay = Integer.parseInt(reader.readLine());
        double moneyPerSearch = Double.parseDouble(reader.readLine());


        double allMoney = 0;
        for (int i = 1; i <= usersCountPerDay; i++) {
            boolean exclusion = false;
            int words = Integer.parseInt(reader.readLine());
            if (words > 5) {
                continue;
            }
            if (words == 1) {
                if (i % 3 == 0) {
                    exclusion = true;
                    allMoney += (moneyPerSearch * 2)* 3;
                } else {
                    exclusion = true;
                    allMoney +=moneyPerSearch *  2;
                }
            } else {
                if (i % 3 == 0) {
                    exclusion = true;
                    allMoney += moneyPerSearch * 3;
                } else {
                    allMoney += moneyPerSearch;
                }
            }


        }

        double result = allMoney * days;
        System.out.printf("Total money earned for %d days: %.2f", days, result);


    }
}