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

public class Solution {

    static long sumOfGroup(int k) {
        // Return the sum of the elements of the k'th group.
        long c = k;
        long upToNow = ((c-1)*c)/2;
        long curr = upToNow * 2 + 1;
        long res = curr*c + 2 * upToNow;
        // curr + curr+2 + curr+4
        return res;
    }

    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();
    }
}