//filename: Main.java

//no package 

import java.util.Scanner;
//some problems require bufferedReader due to a lot of IO, but scanner's usually fine
//reference for buffered IO: https://onlinejudge.org/data/p100.java.html

class Main{
//class should be named Main
//class should not be public, I don't know why
//having multiple classes is fine

        public static void main(String args[]){
                
                Scanner scan = new Scanner(System.in);
                //use System.in regardless of the program mentioning an input file or not
                
                int n = scan.nextInt();
                //scan stuff
                
                System.out.println(3*n+1);
        //print stuff

        scan.close();
                //you seemingly don't have to close the scanner
                //because I constantly forget to and it's still accepted

                //to stop program just have method finish
                //or System.exit(0);
        }
}