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 sum =0;
        int kpos=0;
        long[] odd= new long[1000000];
        int test = 0;
        if(k>=1 && k<=1000000){
            for(int i=0; i< 1000000 ;i++){
            if((i%2)==1){
                odd[test]=i;
                test++;
             }
            }
            
            for(int j=0;j<k;j++){
                kpos +=j;
            }
            for(int m=0;m<k;m++){
                   sum += odd[kpos+m];
                }
                
        }
        
        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();
    }
}