import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner userInput = new Scanner(System.in);

        int humanYears = Integer.parseInt(userInput.nextLine());
        int dogYears = 0;

        if (humanYears >= 1 && humanYears <= 15) {

            dogYears = humanYears * 7;

//            if (humanYears < 2) {
//                dogYears = humanYears * 10;
//            } else {
//                dogYears = humanYears * 4;
//
//            }
            System.out.println(dogYears);
        }


    }
}