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 start=1,sum=0;
        long[] sumarr=new long[k+1];
        for(int i=0;i<=k;i++)
        {   sum=0;
            for(int j=0;j<i;j++)
            {sum+=start;start+=2;}
            sumarr[i]=sum;
        }
        //for(int m=0;m<=k;m++){System.out.println(sumarr[m]);}
        return sumarr[k];
    }

    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();
    }
}