import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static long sumOfGroup(int k) {
        
        


		int strtNum = (((k*(k+1))/2)-k)+4;
		//System.out.println("Start num is "+strtNum);
		int sum =0;
		for(int i = 0; i < k; i++){

			sum += strtNum+2;

		}
		return sum;
	
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int k = in.nextInt();
        long answer = sumOfGroup(k);
        System.out.println(answer);
        in.close();
    }
}