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

public class Solution {

    static long sumOfGroup(int k) {
      long loop= 0;
        long suma =0;
        long inic=1;
        long count=0;
        for(int i = 0; i<K;i++){
            final =0;
            suma=0;
            do{
                suma+=inic;
                count ++;
                inic=inic+2;
                if(count = k )Final=1;
            }while(final!=0)     
                if(i==k+1)return suma;
        }
    }

    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();
    }
}