import java.util.Scanner;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */


/**
 *
 * @author Hussein Awala
 */
public class JavaApplication88 {

    /**
     * @param args the command line arguments
     */
   static long get(long k)
    {
        long i= (k)*(k-1)+1;
       /* for (int j = 1; j < k; j++) {
            i=i+2;
        }
        return i;*/
       i=i*k+i-1;
       return i;
    }
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner s=new Scanner(System.in);
        System.out.println(get(s.nextLong()));
    }
    
}