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

public class Solution {

    static BigInteger sumOfGroup(int k) {
        if (k == 1) return BigInteger.valueOf(1);
        if (k == 2) return BigInteger.valueOf(8);
        BigInteger start = (BigInteger.valueOf(k).multiply(BigInteger.valueOf(k-1))).add(BigInteger.valueOf(1));
        return (start.add(BigInteger.valueOf(k - 1))).multiply(BigInteger.valueOf(k));
    }

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